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Although organometallic porous polymer networks are recognized as promising heterogeneous catalysts, the relationship between ligand/monomer geometry and network parameters is usually not well understood due to the lack of atom-resolved characterization methods for the amorphous network matrix. In this work, a series of copper(II) salen-type metal complexes was synthesized, using trans- and cis-1,2-diaminocyclohexane segments, and thoroughly characterized by single-crystal X-ray diffraction and solution- and solid-state NMR spectroscopy. Terminal ethynyl groups of the complexes were then transformed into polyacetylene chains by coordination chain-growth homopolymerization, resulting in highly porous (458–655 m2 g−1) organometallic polymer networks with a copper(II) ion content of about 12 wt%. The presence of paramagnetic copper(II) moieties in these complexes and respective polymer networks required the application of tailored NMR techniques, which together with X-ray crystallography and DFT calculations of the paramagnetic NMR shifts made it possible to investigate the differences in the complex geometry in liquid, powder and crystalline form and compare it with the complex geometry in polymer networks. All prepared organometallic polymer networks were also tested as heterogeneous catalysts for styrene oxidation with uncommonly high substrate conversions and compared with their low-molecular-weight analogues. The high reusability of such heterogeneous polymer-based catalysts was also proven. [ABSTRACT FROM AUTHOR]

Porous molecular crystals (PMCs) have gained significant importance as next-generation functional porous materials. However, the selective crystallisation of the PMC phase remains a challenge. Herein, we have systematically controlled the stability of the luminescent PMC phase prepared using the luminescent Pt(II) complex [Pt(pbim)(N^O)] (pbim = 2-phenylbenzimidazolate, N^O = N-heteroaryl carboxylate) with Pt⋯Pt electronic interactions. The PMC phase formation varied significantly among the complexes depending on the heteroaryl group of the ancillary N^O ligand; the oxazolyl-bearing complex did not form a PMC phase, whereas the pyrazyl- and 5-fluoropyridyl-bearing complexes spontaneously formed a porous structure. This difference was rationalised by the π-stacking capability of the heteroaryl group of the ancillary ligand. Furthermore, owing to the presence of the one-dimensional Pt⋯Pt chains in this PMC phase, the photophysical properties of PMCs resulting from the Pt⋯Pt interactions were also significantly changed by the ancillary ligands. [ABSTRACT FROM AUTHOR]

Two dinuclear double oxygen-bridged iron(III) complexes made of the Fe2(μ2-OR)2 diamond-core cluster resulting from the coordination between iron(III) cations with calix[4]arene ligands and bearing two lower-rim-appended salicylideneamine (4) or o-methoxy-salicylideneamine coordinating sites (5), connected to the macrocyclic platform via three methylene bridges and displaying a salen-type coordination pocket, were synthesized and characterized using single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), high-resolution mass spectrometry (HRESI-MS), IR, TG-DSC and EA techniques. Independent of the presence of the o-methoxy group in the salicylideneamine moieties, the as-formed complexes contained two nonequivalent iron(III) atoms, both adopting a distorted octahedral coordination N2O4-environment but differing in the cis and trans positions of the nitrogen atoms within the metal coordination sphere, as attested by single-crystal X-ray diffraction and DFT-B3LYP calculations. The possible reason for the observed coordination mode of the macrocyclic ligands is their conformational behavior upon coordination with Fe(III) cations, as confirmed by DFT-B3LYP analysis. 57Fe Mössbauer spectroscopy study showed that both Fe(III) atoms were present in high spin states at room temperature and at 80 K in the studied coordination compounds. The methoxy groups located at the ortho position of the salicylideneamine coordinating fragments were observed to influence the energy of the frontier orbitals, resulting in an increase in the bandgap energy from 1.97 eV to 2.07 eV, as experimentally established by solid-state voltammetry study of 42-Fe2 exp and 52-Fe2 exp, respectively. The interplay between the steric and electronic factors, emerging from the o-methoxy group within coordinating salicylideneamine moieties, seemed to have a negligible effect on the electronic properties of the prepared clusters but significantly impacted the frontier orbital energy distribution, according to both experimental data and theoretical calculations. [ABSTRACT FROM AUTHOR]

A series of Cd(II) complexes, [(PPh3)2Cd(SCOf)2] (1), [PPh4]2[Cd(SCOf)2(μ-Br)]2 (2), [(PPh3)2Ag(μ2-SCOf)2Cd(SCOf)] (3), Na2[(PPh3)Cd(MeOH)(SCOf)3]2 (4a) and Na2[(PPh3)Cd(SCOf)3]2.C7H8 (4b) (Where SCOf = furan-2-thiocarboxylate), have been synthesized and characterized by single crystal X-ray analysis and other spectroscopic techniques. Complexes 1 and 2 show distorted tetrahedral and distorted trigonal bipyramidal geometries around Cd(II), respectively. In the case of 3, Cd(II) exhibits a trigonal prismatic structure, whereas, Ag(I) is at the center of a distorted tetrahedron. Complex 4, has a trigonal pyramidal geometry, hitherto unknown for a Cd(II) center. The catalytic activities of complexes for the synthesis of dihydropyrimidinone have been investigated. Out of four complexes, complex 4 is the most efficient catalyst for the one-pot multicomponent Biginelli-type coupling toward the synthesis of dihydropyrimidinone. Excellent yields of the desired products were obtained with very low catalyst loadings (1 mol%). With a few examples, the versatility and scope of the method have also been demonstrated. The catalysts were also tested for their recyclability. [ABSTRACT FROM AUTHOR]

With the consecutive development of space missions, deep wells, and other specialized applications, the creation of new-generation heat-resistant energetic materials bearing high stability to satisfy the harsh requirements of the above application scenarios is crucial. Inspired by three types of structure reinforcements abounding in heat-resistant explosives, namely, weak interaction, azo moiety, and coordination, we attempted to simultaneously integrate them within one molecule to improve stability. Consequently, we employed the 5,5′-diamino-3,3′-azo-1H-1,2,4-triazole (H2DAAT) ligand to obtain a 3D solvent-free energetic metal–organic framework (EMOF) [Cd(DAAT)]n (1). Structurally, both N atoms of the azo moiety in the DAAT2− ligands simultaneously coordinated with Cd(II) ions to form a bis-five-membered ring by the μ2-bridged trans-coordination style, which was rarely reported before in the territory of EMOFs. This intriguing trait may enhance the stability of the two EMOFs by reducing the probability of metal ions coordinating with the solvent molecules. Surprisingly, the thermal decomposition temperature of 1 (Td = 404 °C) is 117 °C higher than that of the ligand (Td = 287 °C). Besides, 1 manifests superb chemical stability (intact in aqueous solutions with pH 1–14 for 15 days), and mechanical stability (IS > 40 J, FS > 360 N). The calculation results show that 1 has a detonation pressure of 33.25 GPa and a detonation velocity of 7941 m s−1. The possible decomposition products were probed by a TG-DSC-MS-IR test. Overall, this work lends concrete support to the design and synthesis of a new-generation of heat-resistant energetic materials. [ABSTRACT FROM AUTHOR]

Thermal expansion regulation by chemical decoration at a molecular level is of great technological value for materials science. Herein, we show that the spin crossover active compound Fe(pyz)Pt(CN)4 (pyz = pyrazine) shows a rare 2D negative thermal expansion (NTE) in the ab-plane. By introducing axial coordination iodine ions or reducing the framework dimension from 3D to 2D, the NTE behavior can be effectively switched to positive thermal expansion (PTE) or even zero thermal expansion (ZTE). Moreover, it is found that different spin states of Fe2+ also influence the magnitude of NTE. Compared with the low-spin (LS) sate, the high-spin (HS) state tends to enhance the magnitude of NTE. Combined in situ structural and Raman spectral analyses revealed that the NTE mainly originates from the transverse vibration of a bridging cyano group and the tailorable thermal expansion is closely related to the state of the Fe–C≡N–Pt linkage. The present study shows how the rational regulation of the building unit and framework dimensions can effectively control thermal expansion behaviors. This insight can serve as guidance for designing and synthesizing novel NTE materials. [ABSTRACT FROM AUTHOR]

The syntheses, structures, luminescence and magnetic properties of a new series of Ln(III) complexes of the formula [Ln(L)(H2O)2(DMF)2][Ln(L)2] (in which H2L is N,N′-ethylaminebis[1-phenyl-3-methyl-4-formylimino-2-pyrazoline-5-one]; Ln(III) – Gd (1), Tb (2), or Dy (3) ions). The crystal structures were determined by single-crystal X-ray diffraction measurements for all the above-mentioned complexes. The crystals of these compounds consist of cationic [Ln(L)(H2O)2(DMF)2]+ and anionic [Ln(L)2] moieties which form a 3D supramolecular architecture by the H-bonds and electrostatic forces. Luminescence emission in the visible range was observed for Tb(III) and Dy(III) compounds upon ligand sensitization, with moderate quantum yields of 3.2% for the Dy complex and 24.2% for the Tb analogue. Moreover the Tb(III) complex demonstrates triboluminescence activity. The dynamic magnetization studies revealed that 1 and 2 demonstrate field-induced magnetic relaxation with effective energy barriers, ΔE‖kB = 24 K (for 1) and 85 K (for 2), while the Dy complex 3 exhibits slow relaxation of magnetization in zero field with an activation energy of 256 K. [ABSTRACT FROM AUTHOR]

An in situ hydrolysis of the P–Cl bonds of the carbophosphazene [{NC(NMe2)}2{NPCl2}] (LPCl2) in the presence of hydrated lanthanide(III) nitrates in a dichloromethane and methanol (2 : 1) solvent mixture afforded a series of novel 1D coordination polymers: [{Ln(LHPO2)3(NO3)2(CH3OH)(H2O)} (Cl)]n {where Ln(III) = Gd (1), Tb (2), Dy (3), or Er (4) and LHPO2 is the hydrolyzed carbophosphazene (LPCl2) ligand}. X-ray crystallographic analysis revealed that complexes 1–4 are isostructural and crystallized in the monoclinic crystal system having P21/c space group. The coordination polymers are formed because of the involvement of the geminal P(O)(OH) moieties of the carbophosphazene ligand. Each lanthanide(III) ion is 9-coordinate (9O) in a distorted muffin geometry. Magnetic measurements revealed that both DyIII and ErIII analogues exhibit field-induced single-molecule magnet (SMM) behavior at 0.8 kOe and 2.2 k Oe, respectively. At such dc fields, the dynamic magnetic susceptibility displays complex behavior with a triple magnetic relaxation contribution for 3, while two contributions were identified for 4. The observed static and dynamic magnetic behavior for complexes 1–4 were further rationalized with the aid of BS-DFT and CASSCF/SO-RASSI/SINGLE_ANISO calculations. [ABSTRACT FROM AUTHOR]

A thiophene-derived Schiff base ligand (E)-2-morpholino-N-(thiophen-2-ylmethylene)ethanamine was used for the synthesis of M(II) complexes, [TEM(M)X2] (M = Co, Cu, Zn; X = Cl; M = Cd, X = Br). Structural characterization of the synthesized complexes revealed distorted tetrahedral geometry around the M(II) center. In vitro investigation of the synthesized ligand and its M(II) complexes showed considerable anti-urease and leishmanicidal potential. The synthesized complexes also exhibited a significant inhibitory effect on urease, with IC50 values in the range of 3.50–8.05 μM. In addition, the docking results were consistent with the experimental results. A preliminary study of human colorectal cancer (HCT), hepatic cancer (HepG2), and breast cancer (MCF-7) cell lines showed marked anticancer activities of these complexes. [ABSTRACT FROM AUTHOR]

A Zn(II) coordination polymer (CP), namely, {[Zn(DTPB)]·DMF}n (H2DTPB = 1-(3,5-di(2H-tetrazol-5-yl)phenyl)-1H-benzeimidazole, Zn-DTPB), was assembled from a new tetrazolyl–benzimidazolyl heterotopic triangular ligand. In Zn-DTPB, the tetrazolyl groups connect the Zn(II) ions into a 2D network with a (4·82) topology, and the 2D network is further interconnected by Zn–N bonds between Zn(II) and benzimidazolyl groups to a 3D framework featuring a 4-connected sra topology. The DMF molecules were tightly encapsulated in the framework and could not be released until the framework decomposed. The framework is stable up to 300 °C and can be retained in water for 72 h. The luminescence in the solid-state and in various solvents was investigated, implying that Zn-DTPB can be used to detect acetone and triethylamine (TEA) in water by fluorescence quenching with good sensitivity and selectivity. Moreover, Zn-DTPB exhibited excellent reproducibility in sensing acetone. Mechanistic studies have shown that the fluorescence quenching of acetone and triethylamine is caused by competitive absorption and structural amorphization, respectively. Interestingly, the amorphous product can be transformed into Zn-DTPB crystals through a solvent-media structural transformation process. [ABSTRACT FROM AUTHOR]

In this study, three different solvent systems have been employed to investigate the effect of reaction parameters on the synthesis of four alkaline earth metal-based MOFs namely [Ca(0.5 1,4-phenyl diacetic acid)2(H2O)DMF]∞ (Ca-MOF-1), [Ca(1,4-naphthalene dicarboxylate)DMF]∞ (Ca-MOF-2), [Ca2(0.5 1,2,4,5-benzene tetracarboxylate)2(H2O)3DMF]∞ (Ca-MOF-3) and [Ca2(2,6-naphthalene dicarboxylate)2(H2O)6]∞ (Ca-MOF-4). The crystal structures of these four MOFs have been resolved through single crystal X-ray analysis and the bulk phase purity of these MOFs was assessed using PXRD and FT-IR analysis. To check the stability of these MOFs, thermogravimetric analysis (TGA) was carried out. To analyze the robustness of these MOFs, the PXRD of the samples was also collected at different pH levels. These MOFs were further explored as Lewis acid catalysts for the alcoholysis of epoxides and the activity of these catalysts depend on the open metal sites present in the MOFs. The catalytic activity follows the order: Ca-MOF-2 > Ca-MOF-4 > Ca-MOF-1 > Ca-MOF-3. The activity was also checked with various epoxide substrates using Ca-MOF-2. Density functional theory (DFT) calculations also support this trend with the help of the thermodynamic feasibility of epoxide binding, considering model MOF structures. The weak interaction between the epoxide oxygen and the metal centre of the most stable MOF structure has also been clarified by computational studies. [ABSTRACT FROM AUTHOR]

Herein, we synthesized three new LMOFs, [Cd(TPPE)0.5(oba)(H2O)]n (LMOF-1), [Cd2(TPPE)(bpdc)2]n (LMOF-2), and [Cd2(TPPE)(sdc)2]n (LMOF-3) (TPPE = 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene, oba = 4,4′-diphenyl ether dicarboxylic acid, bpdc = 4,4′-biphenyl dicarboxylic acid, sdc = 4,4′-styrene dicarboxylic acid), with high quantum yields of 43.74%, 36.68% and 45.89%, respectively, exceeding those reported for most Cd-based LMOFs. All three LMOFs have good detection sensitivity for Fe3+, CrO42− and Cr2O72−. Surprisingly, Na+ can rarely but significantly enhance the fluorescence intensity of LMOF-3, and the detection limit is 1.90 × 10−5 M. This is the first reported LMOF material that can quantitatively analyze Na+ among references. All results indicate that the three MOFs can be developed into phosphor materials and fluorescent chemical sensors for detecting ions in water. [ABSTRACT FROM AUTHOR]

Nanozymes show great potential in organic degradation because of their good stability and low cost. However, their poor catalytic activity and functional diversity restrict their practical applications. The present study reports the synthesis of a Pt/Co/Co3O4/EW-GQD nanozyme via the coordination of Co2+ and Pt4+ with a glutamate and tryptophan-functionalized graphene quantum dot (EW-GQD) and subsequent thermal reduction and part oxidation. The graphene surface ligand engineering creates a reactive microenvironment similar to natural enzymes, facilitating a high-speed electron-transfer process from Co3O4 to graphene and strong adsorption capacity toward rhodamine B. The Co and Pt double doping narrows the bandgap and leads to an improved electronic conductivity. The Pt/Co/Co3O4/EW-GQD nanozyme exhibited a peroxidase-like specific activity of 1662.67 U mg−1 and oxidase-like specific activity of 293.45 U mg−1, which exceed by 3.2-fold that of horseradish peroxidase and by 15.6-fold that of choline oxidase. This enabled a 3.6-fold increase in the degradation efficiency of rhodamine B without the need for an activator. The high catalytic activity was mainly attributed to the perfect combination of the graphene surface ligand and Co and Pt double engineering, which produced multiple active sites such as Co3+/Co2+, Pt4+/Pt2+, and pyrrolic N/pyridinic N and multiple active species such as 1O2, ˙O2−, and ˙OH. This work introduces a novel way for the design and synthesis of nanozymes with excellent catalytic activity and multifunctional performance. [ABSTRACT FROM AUTHOR]

Decatungstate (W10O324−, DT) is a metastable polyoxometalate anion which presents excellent photocatalytic ability. In order to stabilize the DT species, four decatungstate-based coordination polymer compounds with different DT coordination modes, namely [Cu2(3-bpo)2(H2O)2(DMSO)2][W10O32]·14H2O (1), [Cu2(3-bpo)2(DMSO)4][W10O32] (2), [Cu2(4,4′-bipy)4][H2W10O32] (3) and [Cu(4,4′-bipy)3(DMSO)(H2O)][TBA][HW10O32]·H2O (4) (DMSO = dimethyl sulfoxide, 3-bpo = 2,5-bis(3-pyridyl)-1,3,4-oxadiazole, 4,4′-bipy = 4,4′-bipyridine, TBA = tetrabutylammonium) were synthesized under controlled solvothermal conditions in the mixed solvent of DMSO and H2O. The heterogeneous photocatalytic activity of these four compounds in the degradation of rhodamine B was tested and the results show that they possess fairly high photocatalytic activity without leaching of DT during the reaction. The effect of the coordination modes of terminal oxygen (Ot) atoms in DT anions on the activity was investigated. [ABSTRACT FROM AUTHOR]

Series of mixed-ligand coordination polymers (CP) and metal–organic frameworks (MOFs) based on bulky 9,10-di(1H-imidazol-1-yl)anthracene (dia) were synthesized from aqueous solutions even with very short (<10 min) reaction times. Two different metals (M = Cu, Ni) and three different secondary ligands were used to generate six new structures: [Cu2(dia)2(5-aip)2]·6H2O (1), [Ni2(dia)2(5-aip)2]·5H2O (2), [Cu2(dia)2(2-ata)2]·4H2O (3), [Ni(dia)(2-ata)·Ni(dia)2(2-ata)]·2.5H2O (4), [Cu8(dia)2(5-sip)4(OH)4] (5) and [Ni3(dia)5(5-sip)2]·6DMF·14H2O (6). Structure analyses involving single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD) and Fourier-transform infrared spectroscopy (FT-IR) were conducted along with studies determining the thermal stabilities and optical properties of the compounds. The results indicate that the developed fast and green syntheses can produce pure CP and MOF phases that have various thermally stable and visible light absorbing structures which may find applications in photocatalysis. [ABSTRACT FROM AUTHOR]

A series of four Cd(II) complexes with 5-methyl-4-imidazolecarboxaldehyde (L) with different inorganic anions within or outside the coordination sphere of general formula: [CdCl2L2] (1), [CdBr2L2] (2), [CdI2L2] (3), and [CdL4](PF6)2·3H2O (4) was synthesized through one-step and two-step reactions, respectively. All complexes were obtained as colorless crystals without the need for recrystallization and exhibited solubility in aqueous solutions. Structural analysis revealed different coordination environments for each complex, with variations in bond lengths and angles. The crystal packing of the complexes was stabilized by hydrogen bonding and π–π stacking interactions. FT-IR analysis indicated coordination of the ligand to the metal ion, and UV-Vis studies confirmed the stability of the complexes in solution. Computational analysis has revealed the polar nature of the complexes and their favorable stability constants. Affinity studies with DNA using the switchSense technique demonstrated rapid association and dissociation processes for all complexes, with temperature-dependent binding constants. Thermodynamic analysis suggested spontaneous with positive entropy change and endothermic formation processes for the complexes. Overall, the study underscores the synthesis, examination, and interaction with DNA of Cd(II) complexes, demonstrating their promise within medicinal chemistry. [ABSTRACT FROM AUTHOR]

Synthesiszing highly catalytically active and stable non noble metal oxygen evolution reaction (OER) catalysts with controlled coordination environments at room temperature and probing the relationship between coordination environments and active centers remain challenging. Herein, a series of monomeric particles composed of different coordination environments, Fe–(NH2)4–C, Fe–(NH2)3/OH–C, Fe–(NH2)/(OH)3–C and Fe–(NH2)2/(OH)2–C, were synthesized by means of the response of chitosan salt (HACC) ionomers to pH values in solution at room temperature. The experimental results show that the active center of amine catalysts enables them to exhibit enhanced performance with a low overpotential of 255 mV at 10 mA cm−2 maintaining favorable stability (only 1.3% loss of current density after 12 h) for the OER in a low amino coordination environment (Fe–NH2/(OH)3–C). Therefore, the selection of a suitable coordination environment is the key to the synthesis of efficient and highly stable ionomer-based catalysts. This work provides a practical reference for the design of efficient catalysts in the future. [ABSTRACT FROM AUTHOR]

Inorganic–organic hybrid semiconductors based on copper(I) halide are intriguing luminescent materials possessing great prospects as rare-earth elements (REEs) free phosphors for use in solid-state lighting (SSL). However, it is still a great challenge to develop such hybrid semiconducting materials with high energy blue light emission and good thermal stability simultaneously. Here, we have synthesized a brand new, one-dimensional (1D) organic–inorganic semiconductor CuI-Pytz (Pytz = 4-(pyrid-2-yl)-1,2,4-triazole) using a solvent diffusion method, for which the structure was determined by single crystal X-ray diffraction (SCXRD) and shows great thermal stability and decomposition temperature up to 220 °C. At room temperature, this indirect band gap hybrid semiconductor shows a blue emission centered at 464 nm which was nearing deep blue light (<460 nm) with a band gap energy of 2.70 eV. In addition, we developed a simple method for large-scale synthesis of the microcrystal, which significantly enhances the possibility of widespread applications for CuI-Pytz. Both density functional theory calculations and experimental studies reveal that the blue light emission originates from the combination of metal-to-ligand charge transfer (MLCT) and halide-to-ligand charge transfer (XLCT). The good thermal stability and high energy blue light emission make this low-cost and easily available copper(I) halide hybrid semiconductor a potential candidate for use as rare-earth free phosphors. [ABSTRACT FROM AUTHOR]

Six new coordination polymers (CPs) of cadmium based on an extended anilate-type ligand, 4,4′-(1,4-phenylenebis(azanylylidene))bis(3,6-di-tert-butyl-2-hydroxycyclohexa-2,5-dienone) (H2L), have been synthesized. The series of coordination polymers includes [Cd(L)(DMF)] (1), 1D-CP [Cd(L)(dipy-1)]·2DMF (2A) and 2D-CP [Cd(L)(dipy-1)]·DMF (2B), [Cd2(L)2(dipy-2)(DMF)2] (3), [Cd(HL)(CH3COO)(dabco)] (4) and [Cd(L)(ur)2]·(H2L) (5) (where L – deprotonated form of H2L, DMF – N,N′-dimethylformamide, dipy-1 – 4,4′-trimethylenedipyridine, dipy-2 – 4,4′-dipyridyl, dabco – 1,4-diazabicyclo[2.2.2]octane, ur – urotropine). The crystal structure and thermal decomposition of 1D- and 2D-coordination polymers are reported. The structural diversity of the synthesized compounds was found to depend on the additional neutral donor ligands in the cadmium coordination sphere. Thus, the introduction of the flexible N-donor ligand dipy-1 into the cadmium coordination sphere leads to the formation of two types of coordination polymers (1D and 2D). The use of the rigid ligand dipy-2 promotes the formation of "honeycomb" 2D-CPs. The use of shorter N-donor ligands dabco and ur leads to linear derivatives in which the ligands being coordinated by cadmium don't act as "crosslinkers" of the chains in the network. [ABSTRACT FROM AUTHOR]

In this work, a new d10-configuration based Cd(II) coordination polymer (CP) with the formula [Cd2(CH3COO)2(bimb)2]·2ClO4 (1) have been synthesized using 4,4′-bis(imidazolyl)biphenyl (bimb) ligand and characterized. Single-crystal X-ray analysis reveals that the CP forms a 2D layer connected to a 3D supramolecular framework with weak packing interactions between benzyl and imidazolyl rings. CP 1 has been used as a photoluminescent sensor and a photocatalyst for the photodegradation of antibiotics, in particular nitrofurantoin (NFT). Sensing experiments indicate that 1 can selectively detect nitrofurantoin with a limit of detection of 0.025 μM, whereas when employed as a photocatalyst, CP 1 can photodecompose NFT up to 91.83% in a time span of 20 min. The decline in the photoluminescence intensity of CP 1 in the presence of NFT and the photocatalytic mechanism are addressed using theoretical calculations. [ABSTRACT FROM AUTHOR]

A new doubly carboxylato-bridged Co(II) dinuclear complex, [Co(bdtbpza)(NCS)]2 (1), was obtained in a satisfactory yield by employing a 'scorpionate'-type precursor, bdtbpza {bis-(3,5-di-tert-butylpyrazol-1-yl)acetate}, and was then structurally characterized. Single-crystal X-ray diffraction analysis revealed that, in 1, each Co(II) is penta-coordinated, leading to a distorted trigonal–bipyramidal geometry within the coordination environment of N3O2. Weak antiferromagnetic coupling within the Co(II) ions in 1 was found based on the isotropic spin Hamiltonian H = −J(S1·S2) for the Si = 3/2 system. For evaluating the spin density distribution and the mechanism for the magnetic exchange coupling, DFT analysis was performed, with the calculated result agreeing the experimental magnetic data. A study into electrochemical H2 evolution, involving cyclic voltammetry (CV), controlled potential electrolysis (CPE), and gas chromatographic (GC) analyses of the graphite electrode modified with the cobalt complex in a neutral aqueous solution revealed the high catalytic activity of the complex with a low overpotential toward H2O reduction. The faradaic efficiency of the catalyst was found to be 83.7% and the di-cobalt catalyst-modified electrode displayed quite an interesting H2-evolution activity compared with that of bare electrodes. These results are encouraging for the future potential application of 1 in water splitting. [ABSTRACT FROM AUTHOR]

Zinc(II)-complexes with the general formula [Zn(L)2] containing 8-hydroxyquinoline Schiff bases functionalized with 1-(3-aminopropyl)imidazole or 1-(3-aminopropyl)-2-methyl-1H-imidazole on 2-position and their respective ligands (HL1 or HL2) were synthesized and characterized by NMR, UV-Vis, FTIR and CD spectroscopies as well as ESI-MS spectrometry. Single crystals of HL2 and [Zn(L1)2]n were analysed by SC-XRD. [Zn(L1)2]n shows a 1D polymeric chain structure of alternating Zn(II) cations and bridging Schiff base ligands, in contrast to previously reported monomeric structures of analogous complexes. DFT calculations were performed to rationalize the polymeric X-ray structure of Zn(L1)2. Results showed that the ligands can bind as bi- or tridentate to Zn(II) and there is the possibility of a dynamic behavior for the complexes in solution. Both ligands and complexes present limited stability in aqueous media, however, in the presence of bovine serum albumin the complexes are stable. Molecular docking simulations and circular dichroism spectroscopic studies suggest binding to this protein in close proximity to the Trp213 residue. Biological studies on a panel of cancer cells revealed that the Zn(II)-complexes have a lower impact on cell viability than cisplatin, except for triple-negative breast cancer cells in which they were comparable. Notwithstanding, they display much higher selectivity towards cancer cells vs. normal cells, than cisplatin. They induce the generation of ROS and DNA double-strand breaks, primarily through apoptosis as the mode of cell death. Overall, the novel Zn(II)-complexes demonstrate improved induction of apoptosis and higher selectivity, particularly for melanoma cells, compared to previously reported analogues, making them promising candidates for clinical application. [ABSTRACT FROM AUTHOR]

A series of coordination polymers (CPs), some of them featuring an unusual architecture, have been constructed by treatment of RSCH2C≡CCH2SR (R = C6H11L1, t-Bu L2) with CuX (X = Cl, Br, I) and CuX2. The outcome of the reaction of L1 with CuI depends on the metal-to-ligand ratio. Treatment of CuI with L1 in a 2 : 1 ratio affords the luminescent 2D CP [Cu4I4(μ-L1)2]n (CP1), whose grid-shaped network is built upon Cu4(μ3-I)4 cubane-like clusters as secondary building units (SBUs), interconnected via bridging L1 ligands. The use of a 1 : 1 ratio gives a material, whose particularity is the coexistence of two topological isomers within the unit cell. The first one, [{Cu(μ2-I)2Cu}(μ-L1)2]n (CP2), consists of 1D ribbons. The second isomer having a 0D topology, [{Cu(μ2-I)2Cu}(μ-L1)2] D1, is built upon discrete molecular complexes, whose dinuclear [Cu(μ2-I)2Cu] rhomboid-shaped core is spanned by two bridging L1 ligands. Mixing CuBr with L1 in MeCN solution leads to an isostructural material incorporating both 0D [{Cu(μ2-Br)2Cu}(μ-L1)2] complex D2 along with the 1D isomer [{Cu(μ2-Br)2Cu}(μ-L1)2]n (CP3). However, only the 1D CP [{Cu(μ2-Cl)2Cu}(μ-L1)2]n (CP4) results from complexation of L1 with CuCl. A stoichiometry-dependence is also noticed upon treatment of CuI with L2. Conducting the reaction in a 2 : 1 ratio yields the luminescent 2D CP [Cu4I4(μ-L2)2]n (CP5), whereas mixing equimolar amounts of the reactants produces 2D CP [{Cu(μ2-I)2Cu}(μ-L2)2]n (CP6). Structurally similar 2D CPs [{Cu(μ2-X)2Cu}(μ-L2)2]n (CP8 and CP9) result from complexation of L2 on CuBr or CuCl, respectively. Treatment of L2 with an excess of CuBr or CuBr2 in refluxing acetonitrile led to the transfer of Br to the acetylenic triple bond, generating an olefinic halogenated dithioether ligand Bu L3 that coordinates to CuBr to generate a 1D network [{Cu(μ2-Br)2Cu}(CH3CN)(μ-L3)]n (CP9). Using different conditions (propionitrile at 293 K), the reaction of L2 and excess CuBr led to the formation of a 2D network [{Cu(μ2-Br)2Cu}(μ-L2)(μ-L3)]n (CP10) incorporating both L2 and L3 in an alternating manner as assembling ligands. An isostructural chloro-analogue 2D [{Cu(μ2-Cl)2Cu}(μ-L2)(μ-L4)]n (CP11) was obtained using CuCl or CuCl2. The crystallographic work is completed by thermal analyses and investigation of the luminescence properties of CP1 and CP5 at 77 and 298 K. [ABSTRACT FROM AUTHOR]

Two new cyanido-bridged {FeIIMII} double chains were obtained by reacting cyanido anions [M(CN)4]2- with complex cations [FeII(tptz)]2+ (preformed in situ by mixing a hydrated tetrafluoroborate salt of iron(II) and a tptz ligand, tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine) having the general formula [FeII(tptz) MII(CN)4]·2H2O·CH3CN, where M = Pd (1) or Pt (2). Additionally, two molecular complexes formulated as [FeII(tptz)2][MII(CN)4]·4.25H2O, where M = Pd (3) or Pt (4), were subsequently obtained from the same reaction, as secondary products. Single crystal X-ray analysis revealed that 1 and 2 are isostructural and crystallize in the P-1 triclinic space group. Their structure consists of a double-chain with a ladder-like topology, in which cyanido-based [M(CN)4]2- metalloligands coordinate, through three CN- ligands and three [FeII(tptz)]2+ complex cations. Compounds 3 and 4 are also isostructural and crystallize in the P1¯ triclinic space group, and the X-ray structural data show the formation of [FeII(tptz)2]2+ and [MII(CN)4]2- ionic units interconnected through H-bonds and π⋯π stacking supramolecular interactions. The static DC magnetic measurements recorded in the temperature range of 2-300 K showed that 1 and 2 exhibit incomplete spin transition on cooling, which is also confirmed by single crystal XRD analysis and Mössbauer spectroscopy. Compounds 3 and 4 are diamagnetic, most likely due to the encapsulation of Fe(II) in a tight pocket formed by two tptz ligands that preserve the low-spin state in the temperature range of 2-400 K. [ABSTRACT FROM AUTHOR]

Metal-organic cages (MOCs) are an emerging class of porous materials with promising applications. However, controlling the configuration of the cage packing, which can influence the overall porosity of the materials, remains a difficulty, as many factors can influence the cage assembly and stacking. Herein, we report a solvent strategy to fine-tune the packing configuration of a bilayer MOC, a small triangular prism cage (six Cu ions act as vertices, three nitrate ions act as pillars, and six nitrate ions act as caps) incorporated into a large triangular prism cage (another six Cu ions act as vertices, a couple of oxygen atoms act as pillars and six ligands (L1: 3,5-bis(pyridine-3-yl)-4H-1,2,4-triazole) act as a jointed cap) by the coordination between the triazole nitrogen from L1 and the inner vertex Cu ions. The involved solvents water, acetonitrile (MeCN) and N,N'-dimethylformamide (DMF) form hydrogen bonds with this bilayer MOC, resulting in three different types of packing associated with systemically tuned porosity (NTU-93: 12.2%, NTU-94: 19.3%, and NTU-95: 42.1%). Gas adsorption and breakthrough tests demonstrate that NTU-95 has potential ability for C2H2/C2H4 separation. This work not only shows a case of finely tuned packing of coordination cages, but also provides a powerful tool that may be extended to other cage families. [ABSTRACT FROM AUTHOR]

A highly reversible Zn metal anode is the prerequisite for realizing the practical applications of aqueous Zn ion batteries (ZIBs), which are limited by severe zinc dendrites and corrosion. Herein, bio-inspired hydroxyl-rich L-ascorbic acid (vitamin C, L-Aa) was employed to regulate coordination chemistry via the strong interaction between –OH and H2O with dual remodeling functions and further improve the reversibility of Zn anodes. Specifically, L-Aa not only reconstructs the Zn2+ solvation shell, thus reducing Zn2+ desolvation energy, but also forms a molecular adsorption interface via excellent zincophilicity to improve zinc redox kinetics and suppress Zn anode corrosion. Meanwhile, the molecular adsorption interface facilitates the homogenization of the interfacial electric field, thereby promoting the predominant deposition of Zn(002). Consequently, the Zn//Cu asymmetric cell presents a low overpotential for zinc nucleation and exceptional average coulombic efficiency (CE) of 99.6% over 1200 cycles at a high current density of 20 mA cm−2. The Zn//Zn cell also delivers excellent cycling stability for over 1400 h at 5 mA cm−2. In addition, the Zn//MnO2 full cell exhibits a robust long-term cycling performance of 1000 cycles at 1 A g−1. This strategy of simultaneously regulating coordination chemistry and further constructing molecular interfaces may boost the applications of highly reversible ZIBs. [ABSTRACT FROM AUTHOR]

Hydrogen bonds are the fundamental factors stabilizing DNA and RNA macromolecules. Based on their base-pair sequences, DNA and RNA perform various biological functions. A key feature of these sequences is their linkage via hydrogen bonds. The hydrogen bonding between sugars and nucleobases in RNA sequences is one of the major reasons behind several mutagenic disorders that can cause numerous genomic instabilities, various genetic diseases, and RNA rearrangement problems. Chemists explore hydrogen bonding stability in nucleic acids, which is crucial for understanding molecular-level differentiations with potential applications in the early diagnosis of hereditary diseases. In this work, five types of coordination polymers of CMP and dCMP, {[Cd(CMP)(bpa)(H2O)3]·2H2O}n (1), {[Cd(dCMP)2(bpa) (H2O)2]·4H2O}n (2), {[Cd(azpy)(H2O)4](CMP)·3H2O}n (3), {[Cd(dCMP)2(azpy)(H2O)2]·4H2O}n (4), and {[Cd(CMP)(bpe)(H2O)3]·2H2O}n (5) (azpy = 4,4'-azopyridine, bpa = 1,2-bis(4-pyridyl)ethane, and bpe = 1,2-bis(4-pyridyl)ethylene), were designed and studied. All complexes were fully characterized by employing the single-crystal X-ray diffraction method. Complex 1 is a 2D coordination polymer, whereas complexes 2-5 are 1D coordination polymers. Significantly, a novel sugar-nucleobase hydrogen bonding interaction was discovered in complexes 1, 3, and 5 for the first time, thus introducing a new supramolecular interaction that can be used in self-assembly and molecular recognition. The chirality in the supramolecular assemblies of the five complexes was comprehensively analyzed using single-crystal and solid-state CD spectra. [ABSTRACT FROM AUTHOR]

Nine lanthanide-organic frameworks [Ln(L)1.5(H2O)3] (1-Ce, 2-Dy, 3-Eu, 4-Gd, 5-Ho, 6-Nd, 7-Pr, 8-Sm, and 9-Tb; H2L = 4,4'-(1,2-dihydroxyethane-1,2-diyl)dibenzoic acid) have been synthesized under solvothermal conditions. Single-crystal X-ray diffraction analyses show that compounds 1-9 are isomorphic, in which each Ln atom is linked by L ligands to form a 3D framework with an unprecedented 4,4,6-connected topology. All these compounds have excellent solvent stability and can remain stable in boiling water for up to a week. Moreover, these compounds exhibit metal-dependent luminescence and magnetic properties. 3-Eu and 9-Tb exhibit relatively good fluorescence properties, 4-Gd shows ferromagnetic coupling, and the other compounds present antiferromagnetic coupling. [ABSTRACT FROM AUTHOR]

We present the synthesis and characterization of two monometallic coordination polymers, [Co(L)2(H2O)2]n (Co-CP) and [Ni(L)2(H2O)2]n (Ni-CP), alongside a heterobimetallic counterpart, CoNi-CP, derived from an amide-based multifunctional pro-ligand 4-(pyrimidin-5-ylcarbamoyl)benzoic acid (HL), and discussed their electrocatalytic activity in the oxygen evolution reaction (OER). The CPs were characterized using various techniques, including elemental analysis, IR spectroscopy, X-ray diffraction, and thermal and powder XRD analyses. The low-cost amide-functionalized transition metal pristine coordination polymers Co-CP and Ni-CP were demonstrated to catalyze the OER in alkaline media, surpassing the benchmark IrO2 electrocatalyst performance. The heterometallic coordination polymer (CoNi-CP) displayed a lower Tafel slope value (and thus, faster kinetics) and higher long-term durability compared to its monometallic counterparts, Co-CP and Ni-CP. The results obtained show a pristine transition metal heterobimetallic coordination polymer as a lowcost electrocatalyst of great promise and high performance for OER catalysis in alkaline media. [ABSTRACT FROM AUTHOR]

Two photochromic Cd(II)-CPs were obtained based on the viologen ligand using different synthetic routes, named {[Cd4(p-BDC)4(CPB)2(H2O)2]·2H2O·EtOH}n (1) and {[Cd(p-BDC)(CPB)(H2O)]·(L)·DMF}n (2) (p-H2BDC = 1,4-benzene-dicarboxylate, HCPB·Cl = 1-(4-carboxyphenyl)-4,4′-bipyridinium·Cl, L = 2,4-dinitrochlorobenzene, and DMF = N,N-dimethylformamide), respectively. Due to different coordination modes, the two Cd(II)-CPs show different structures. Compound 1 exhibits a three-dimensional (3D) framework with bimetallic nodes, while compound 2 displays a 2-fold interpenetrated (4,4) net topology. Notably, the two Cd(II)-CPs exhibit substantial disparities in photo/thermochromism, which can be attributed to variations in donor–acceptor (D–A) distances arising from structural differences. Compound 1 showed visually sensitive photo- and thermochromic behavior due to multi-pathway electron transfer and short D–A distances, which is relatively rare in electron-transfer type photochromic systems. In contrast, 2 only demonstrates insensitive photochromic behavior, with a slight deepening of the color observed after 2 hours of UV light, which is due to the mono-pathway electron transfer and long D–A distance. Moreover, we first combined Cd(II)-viologen CPs with polydimethylsiloxane (PDMS) to prepare a 1@PDMS flexible UV imaging film. 1@PDMS exhibits excellent bendability and stretchability and maintains good photochromic properties after 100 bending cycles. To demonstrate the rapid color response and distinct color contrast of 1, its application in anti-counterfeiting is also demonstrated. [ABSTRACT FROM AUTHOR]

In this study, the structural, electronic, and vibrational properties of the thinnest crystal structure that can be obtained by thinning bulk Cd down to a monolayer are investigated by performing first-principles calculations. Total energy optimization and dynamic stability calculations reveal that the single layer crystal structure has a hexagonal unitcell with a two-atomic basis where alternating layers are formed by trigonal arrangements of Cd atoms. Softening occurs with decreasing zone center optical phonon frequencies as a result of structural relaxation when going from a bulk to a single layer (SL) structure. It is also shown that the thinnest structure obtained from bulk Cd crystals maintains its metallic features despite the dimensional crossover. In addition, it is predicted through calculations that the SL Cd crystal strongly interacts with oxygen and that the oxidized regions even undergo chemical transformation to form a CdO crystal. In the double-layer CdO crystal resulting from the oxidation of individual Cd layers, the layers are connected to each other with partially covalent bonds, and this structure is a semiconductor with a band gap of 2.10 eV. On the one hand, the robust metallic structure of the thinnest possible Cd crystal provides flexibility for its use in nanoscale applications, on the other hand, the fact that its electronic properties can be changed by oxidation is important for optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Two new Zn(II) coordination complexes, namely [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2), were synthesized and designed as self-assembled vaccine candidates against the SARS-CoV-2 receptor-binding domain (RBD) protein and Omicron spike protein (where L = (Z)-N-phenyl-N′-((Z)-phenyl(pyridin-2-yl)methylene)carbamohydrazonic acid, and en = ethylenediamine). Both the Zn(II) complexes were fully characterized using single-crystal X-ray crystallography, cyclic voltammetry, FT-IR spectroscopy, FT-Raman spectroscopy, NMR spectroscopy, UV-Vis and fluorescence spectroscopic experimental techniques and density functional theory calculations. Both the complexes were crystallized in the monoclinic crystal system with the P21/n space group. Crystallographic studies indicated a square pyramidal geometry for [Zn(L)(en)]ClO4 (1) and distorted octahedral for [Zn(L)2] (2). DFT calculations were performed to provide information on the structure–activity relationships. Hirshfeld surface (HS) analysis was also performed. The interactions of the Zn(II) complexes [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2) with CT-DNA were followed by UV-Vis studies. Absorption titration studies revealed that these interacted strongly with CT-DNA. The calculated equilibrium binding constant (Kb) values found were to be 4.75 × 104 and 5.82 × 104 L mol−1 for [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2), respectively. The in vitro cytotoxicity and antibacterial potential of [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2) were studied. In order to gain an insight into the potential applications of the Zn(II) complexes as effective antivirus agents, we performed molecular docking of [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2) with the SARS-CoV-2 (PDB ID: 7LM9) receptor-binding domain (RBD) protein and the Omicron spike protein (PDB ID: 7WOP). The Zn(II) complexes demonstrated similar antivirus effects as ivermectin and levosalbutamol. Therefore, we also docked the control ivermectin (IVM) and levosalbutamol (LVM) with both the SARS-CoV-2 RBD protein (PDB ID: 7LM9) and the Omicron spike (S) protein (PDB ID: 7WOP). The synthesized Zn(II) complexes showed good docking results with the SARS-CoV-2 RBD protein and the Omicron spike (S) protein, suggesting they have the potential as drugs for use against SARS-CoV-2 and its Omicron variants. Molecular docking calculations of [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2) with DNA binding protein (PDB ID: 7UV7) showed that these interact with DNA via a groove binding mode. Overall, our molecular docking results showed that the synthesized Zn(II) complexes [Zn(L)(en)]ClO4 (1) and [Zn(L)2] (2) could be adopted as potential inhibitors for the development of new anti-SARS-CoV-2 Omicron drugs. [ABSTRACT FROM AUTHOR]

In this work, three coordination polymers (CPs) were synthesized from Zn2+/Cd2+, fluorescent di-9,10-(imidazolyl)-anthracene (dia), and cyclohexane-1,4-dicarboxylic acid (H2cda). The coordination polymer 1, [Zn(dia)(cda2−)0.5(Hcda−)·0.5H2O]n, contained a layered structure. The coordination polymer 2, [Zn(dia)(cda2−)]n, contained a rare 3D network with a self-catenation pattern. The coordination polymer 3, [Cd2(dia)1.5(cda2−)2]n, contained a 3D network of ose topology. Coordination polymers 1, 2 and 3 were all highly fluorescent. Mixed matrix membranes, prepared by dispersing particles of 1, 2 or 3 within a matrix of polymethyl methacrylate, showed high sensitivity, selectivity and recyclability for detecting Cr2O72− in water. [ABSTRACT FROM AUTHOR]

Using the mixed-ligand strategy, three metal–organic frameworks were constructed by virtue of the solvothermal reaction. These compounds exhibit similar two-dimensional layered structures and serve as an efficient and economical porous heterogeneous catalyst for Knoevenagel condensation under mild conditions. The yields of Knoevenagel condensation can be reached between 96% and 99% in the presence of catalysts 1–3. Notably, the catalytic performance of 1 through reusability was explored, and it was observed that 1 could be reused up to six cycles with almost consistent catalytic efficiency. [ABSTRACT FROM AUTHOR]

Herein, we report two autologous phosphates for electrocatalytic water oxidation. Although they have many similarities, the four-coordinated Co sites in Co3(PO4)2 showed higher activity than the six-coordinated Co sites in Co3(OH)2(HPO4)2. This was because the four-coordination CoII possessed a high turnover frequency and could be easily transformed into high-valent active cobalt (hydr)oxide species. [ABSTRACT FROM AUTHOR]

Coordination polymers (CPs) with a d10-configuration containing metal cations offer interesting photoluminescent properties and hence can be employed as sensors to detect various classes of analytes. Moreover, due to their tuneable pore size they can be employed as adsorbents for various species. Herein, a new d10-configuration Cd(II)-based CP with composition {[Cd(bip)4(H2O)2]n·2NO3} (1) (bip = 3,5-bis(1-imidazol)pyridine) has been synthesized and characterized. Single-crystal X-ray analysis reveals that the Cd(II) center adopts octahedral geometry that is satisfied by four N atoms from the four bip linkers and two aqua ligands, and the resultant CP displays sql topology with the point symbol of (44·62). The CP offers prospective application as a photoluminescent sensor for dichromate anions with a limit of detection of 1.28 ppm and a Stern–Volmer constant (KSV) of 1.51 × 105. Furthermore, CP 1 was employed as an efficient adsorbent for dichromate ions, reaching an equilibrium adsorption capacity of 389.82 mg g−1 within 80 min. The effects of temperature, pH and concentration of dichromate were further investigated, which revealed that CP 1 displays the best adsorption at 30 °C and pH 4 with a dichromate concentration of 200 mg L−1. The possible adsorption mechanism has been proposed with the aid of Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Two 3D coordination polymers based on dinuclear dianionic helicates, K2[MII2(L)3] M = MnII (1) and NiII (2), were obtained by slow liquid–liquid diffusion of solutions of 2-hydroxy-5-nitrobenzaldehyde, 4,4′-methylenedianiline, KOtBu and the metal salt at room temperature. The resulting dianionic triply stranded helicates self-assemble into novel 3D coordination polymers, in which the helicate units act as connectors. The assembly is promoted by the phenolate bridging ability and the coordination of the pre-organized NO2 groups to K–(O–N–O)4–K nodes, resulting in robust paramagnetic materials. SC-XRD shows that the metal centers are located 11.257(2) and 11.264(1) Å apart. The Mn–L bond lengths correspond to the high-spin (HS, S = 5/2) state for 1. The magnetic behavior for both complexes shows weak magnetic exchange, as expected due to the spin carrier separation, and the confirmation of the HS-sate for the MnII centers. For complex 1, an antiferromagnetic exchange is detected, whereas for complex 2, a mixture of intramolecular antiferromagnetic and intermolecular ferromagnetic exchanges are detected. Thus, we demonstrated that nitro groups can be used for the stabilization of anionic complexes because coordination to K+ results in stable intricate architectures. [ABSTRACT FROM AUTHOR]

Two 5-nitroisophthalate (NIPA) based cobalt(II) coordination polymers [Co(4-ABPT)(NIPA)(H2O)3], SSICG-6 (4-ABPT = 3,5-di(pyridine-4-yl)-4H-1,2,4-triazol-4-amine, SSICG stands for solid-state and inorganic chemistry group) and [Co(4-ABPT)(NIPA)(H2O)], SSICG-7, have been synthesized using a mixed ligand approach. Strategic utilization of H2NIPA enables tunability in framework formation and generates coordinated water containing coordination polymers. The –NO2 group in H2NIPA is unlikely to bind directly with metal ions but draws solvent molecules near the metal center via H-bonding. The coordinated water molecules in SSICG-6 and 7 are reversible in nature, resulting in unsaturated metal centers that serve as excellent heterogeneous catalysts in CO2 cycloaddition and tone-pot Hantzsch condensation reactions. The near quantitative conversion of epichlorohydrin into its corresponding carbonate compound was successfully accomplished, employing SSICG-6 as a catalyst under solvent-free conditions. The unique coordination characteristics of SSICG-6 enhance its catalytic efficiency for larger substrates in CO2 cycloaddition reactions compared to other one-dimensional polymers. [ABSTRACT FROM AUTHOR]

Developing high performance noble-metal-free electrocatalysts as an alternative to Pt-based catalysts for the oxygen reduction reaction (ORR) in energy conversion devices is highly desirable. We report herein the preparation of a coordination-polymer (CP)-derived Fe/CP/C composite as an electrocatalyst for the ORR with excellent activity and stability both in solution and in Zn-air batteries. The Fe/CP/C catalyst was obtained from the pyrolysis of an iron porphyrin Fe(TPP)Cl (5,10,15,20-tetraphenyl-21H, 23H-porphyrin iron(III) chloride) grafted Zn-coordination polymer with dangling functional groups 4,4'-oxybisbenzoic acid and 4,4'-bipyridine ligands. The Fe/CP/C catalyst showed much higher ORR activity with a half-wave potential (E1/2) of 0.90 V (vs. RHE) than the Fe/C catalyst (E1/2 = 0.85 V) derived from the carbon-blacksupported Fe porphyrins in 0.1 M KOH solution. When Fe/CP/C was used as the cathode electrocatalyst in Zn-air batteries (ZABs), the ZABs achieved a significantly higher open circuit voltage (OCV = 1.43 V) and maximum power density (Pmax = 142.8 mW cm-2) compared with Fe/C (OCV = 1.38 V, Pmax = 104.5 mW cm-2) and commercial 20 wt% Pt/C (OCV = 1.41 V, Pmax = 117.6 mW cm-2). Using dangling functional groups in CP to increase the loading efficiency of iron porphyrins offered a facile method to prepare high-performance noble-metal-free electrocatalysts for the ORR, which may provide promising applications to energy conversion devices. [ABSTRACT FROM AUTHOR]

A novel series of one-dimensional coordination polymers (CPs) is achieved via a facile one-pot synthesis strategy employing the nitrate salts of trivalent lanthanides, a pentadentate chelating ligand, and triphenylphosphine oxide at a controlled stoichiometry under ambient conditions. All the CPs are characterized comprehensively using spectroscopic, X-ray crystallographic and magnetometric studies. The CPs are found to be thermally stable up to a significantly high temperature and resistant to water for an indefinite time. They are photoactive and exhibit selective fluoride ion (F-) sensing with excellent efficiency both colorimetrically and fluorimetrically in the solid-state as well as in solution. The presence of F- concomitantly sensitizes the photoluminescence enhancement and visual decolourization of the CPs in solution owing to the ground-state intra-molecular proton transfer. The photophysical response of the CPs to F- in solution was found to be instantaneous (<30 s). The sensitivity of detection is observed to be significantly high over a wide range of F- concentrations, covering the beneficial and detrimental domains of F- concentrations in drinking water. The limit of detection (LoD) under ambient conditions was found to be in the micromolar (µM) range--the best being 0.22 µM found using UV-vis spectrometry and 7.5 µM using fluorimetry. In comparison, the USEPA standard cut-off for the upper limit of F- concentration in drinking water is 211 µM, and the LoD of measuring F- concentration using the USEPA standard method using a fluoride-selective electrode is 26.3 µM. The CPs display markedly high selectivity toward F- with negligible-to-no interference from the commonly abundant ions (Cl-, Br-, I-, CH3CO2-, CO32-, SO42-,HPO42-, NH4+, Na+, K+, Mg2+, and Ca2+) in terms of UV-vis spectral change. Moreover, they also exhibit solid-state IR-spectrometric sensitivity towards F- under ambient conditions. [ABSTRACT FROM AUTHOR]

A series of two-dimensional (2D) spin-crossover coordination polymers (SCO-CPs) [FeII(TPE)(NCX)2]·solv (1: X = BH3, solv = H2O·2CH3OH·DMF; 2: X = Se, solv = H2O·2CH3OH·0.5DMF; 3: X = S, solv = H2O·2CH3OH·0.5DMF) were synthesized by employing 1,1,2,2-tetra(pyridin-4-yl)ethene (TPE) and pseudohalide (NCX-) coligands. Magnetic measurements indicated that complexes 1-3 exhibited SCO behaviors with diminishing thermal hysteresis (7/4/0 K) upon decreasing the ligand-field strength. The critical temperatures (Tc) during spin transition were found to be inversely proportional to the coordination ability parameters (a™) with a linear correlation. The guest effect was also investigated in the solvent-exchanged phases 1-SE/2-SE/3-SE wherein the DMF molecules were replaced by methanol molecules. Compared with 1-3, 1-SE/2-SE/3-SE displayed more abrupt and complete single-step SCO behaviors but narrower thermal hysteretic loops. The results reported here demonstrate that the Tc values of these two families were dominated by the ligand-field strength of the NCX- anions (NCBH3 > NCSe > NCS), whereas the guest effect only modulated the kinetic factor of the SCO nature in this system. [ABSTRACT FROM AUTHOR]

The construction of sulfur-incorporated cluster-based coordination polymers was limited and underexplored due to the lack of efficient synthetic routes. Herein, we report facile mechanochemical ways toward a new series of SFe3(CO)9-based dipyridyl-Cu polymers by three-component reactions of [Et4N]2[SFe3(CO)9] ([Et4N]2[1]) and [Cu(MeCN)4][BF4] with conjugated or conjugation-interrupted dipyridyl ligands, 1,2-bis(4-pyridyl)ethylene (bpee), 1,2-bis(4-pyridyl)ethane (bpea), 4,4'-dipyridyl (dpy), or 1,3-bis (4-pyridyl)propane (bpp), respectively. X-ray analysis showed that bpee-containing 2D polymers demonstrated unique SFe3(CO)9 cluster-armed and cluster-one-armed coordination modes via the hypervalent µ5-S atom. These S-Fe-Cu polymers could undergo flexible structural transformations with the change of cluster bonding modes by grinding with stoichiometric amounts of dipyridyls or 1/[Cu(MeCN)4]+. They exhibited semiconducting behaviors with low energy gaps of 1.55-1.79 eV and good electrical conductivities of 3.26 × 10-8-1.48 × 10-6 S cm-1, tuned by the SFe3(CO)9 cluster bonding modes accompanied by secondary interactions in the solid state. The electron transport efficiency of these polymers was further elucidated by solidstate packing, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), density of states (DOS), and crystal orbital Hamilton population (COHP) analysis. Finally, the solid-state electrochemistry of these polymers demonstrated redox-active behaviors with cathodically-shifted patterns compared to that of [Et4N]2[1], showing that their efficient electron communication was effectively enhanced by introducing 1 and dipyridyls as hybrid ligands into Cu+-containing networks. [ABSTRACT FROM AUTHOR]

Reactions between 1,2-di(tetrazol-2-yl)ethane (ebtz), 1,6-di(tetrazol-2-yl)hexane (hbtz) or 1,1′-di(tetrazol-1-yl)methane (1ditz) and Fe(BF4)2 in the presence of adiponitrile (ADN), glutaronitrile (GLN) or suberonitrile (SUN) resulted in the formation of coordination polymers [Fe(μ-ebtz)2(μ-ADN)](BF4)2 (1), [Fe(μ-hbtz)2(μ-ADN)](BF4)2 (2), [Fe(μ-1ditz)2(GLN)2](BF4)2·GLN (3) and [Fe(μ-1ditz)2(μ-SUN)](BF4)2·SUN (4). It was established that the application of dinitriles allows an increase in the dimensionality of the ebtz and hbtz based systems while maintaining the structure of the polymeric units characteristic of previously studied mononitrile based analogues. In 3 and 4, regardless of the type of dinitrile coligand, the motif of 2D polymeric layers constituted by 1ditz molecules remains preserved. However, the dimensionality of 1ditz based networks is governed by the coordination modes of dinitriles. 3, based on a shorter molecule of glutaronitrile, crystallizes as a two-dimensional (2D) coordination polymer. In this compound, dinitriles coordinate monodentately or play the role of guest molecules. The substitution of glutaronitrile with suberonitrile enables the bridging of neighboring polymeric layers, resulting in a 3D network. The intentional selection of bis(tetrazoles) and dinitriles as building blocks has led, as expected, to obtaining systems with the structure of the first coordination sphere consisting of four tetrazole rings and two axially coordinated nitrile molecules. It created the conditions required for the occurrence of thermally induced spin crossover. Magnetic measurements and single crystal X-ray diffraction studies were used for the characterization of the spin crossover properties of 1–4. [ABSTRACT FROM AUTHOR]

Four salts of an anionic iron(III) bis-complex, [Fe(L L -thr)2]1−, were synthesized from water or methanol. H2L L -thr is a tridentate ligand derived from the L -threonine amino acid, and the cations used are Li+ (1), Na+ (2), K+ (3), and Ba2+ (4). Single-crystal X-ray diffraction showed that all the complexes are coordination polymers of different dimensionalities. The iron(III) complex binds to cations through its coordinated phenolate and non-coordinated carboxylate oxygen atoms. While Li+ forms a linear chain, all others have a pair of bridged cations intervening the iron(III) complexes. The 3D network of Ba2+ salt has a sizeable solvent-accessible space occupied by aquated chloride ions. The differences in circular dichroism (CD) spectra and significantly lower conductance values in water and methanol support partial retention of the polymeric nature in methanol. The visible spectra of 4 in methanol or water showed an ∼10 nm shift of the charge transfer bands from 3. However, the addition of Al3+ salt to 2 showed a significant colour shift. Further investigation confirmed that the colour shift is due to partial protonation of the complex with protons generated from salt hydrolysis. Most reports on visual aluminium detection consider aluminium's binding as the shift's source. The present results show that protonation due to hydrolysis of aluminium salt can skew the observation. [ABSTRACT FROM AUTHOR]

The construction of multifunctional metal-organic frameworks (MOFs) has attracted considerable attention. Two novel Dy-MOFs namely [Dy2(TPTC-2OMe)1.5(H2O)4·H2O]n (1) and {[Dy2(TPTC-2OMe)(H2TPTC-2OMe) (H2O)2]·2H2O}n (2) were obtained by a solvothermal method using 2′,5′-dimethoxy-[1,1′:4′,1″-terphenyl]- 4,4″-dicarboxylic acid (H4TPTC-2OMe) as the ligand. Structure analysis demonstrates that both MOFs 1 and 2 displayed three-dimensional framework structures, in which MOF 1 was with Dy(III) metal chains as nodes, while MOF 2 was with Dy2 binuclear metal clusters as nodes. Interestingly, MOFs 1 and 2 exhibited high thermal and chemistry stabilities and presented relatively high proton conductivity (σ) values of 1.69 × 10-4 S cm-1 and 3.52 × 10-6 S cm-1 at 50 °C and 98% RH. Although there exist a large number of coordinated or free H2O molecules in both structures, it is easier to form an ordered hydrogen-bonding network between the coordinated H2O molecules in the structure of MOFs, resulting in a more excellent proton conductivity of MOF 1. Moreover, MOF 1 exhibited field-induced single-molecule magnet (SMM) behavior with energy barriers (Ueff) of 37.22 K (τ0 = 9.27 × 10-8 s). Furthermore, MOF 1 exhibits obvious second-order nonlinear optical properties. This research provides guidance for the design of novelty multifunctional MOF materials. [ABSTRACT FROM AUTHOR]

A semi-flexible imidazole-based urea ligand, 1-(3-(1H-imidazol-1-yl)propyl)-3-phenylurea, and three zincdicarboxylate coordination polymers possessing the ligand were synthesized and characterized. The stoichiometry and coordination number of the zinc(II) ions in the coordination polymers were found to be dependent on the positional isomers of the benzene dicarboxylate. The 1,3-benzenedicarboxylate-based coordination polymer has a one-dimensional structure, whereas, the one possessing 1,4-benzenedicarboxylate has a two-dimensional architecture. The solvent used in the synthesis of the zinc-1,3-benzenedicarboxylate coordination polymer with the ligand played a decisive role on the solvation and conformation of the ligand. The anhydrous form was obtained from a reaction in methanol in which one of the urea moieties has a puckered geometry and the assembly has layers from one-dimensional bunches of coordination chains. However, the same reaction in ethanol provided a solvate having water and ethanol as the solvents of crystallization and it has the two ligands with a stretched geometry forming a cleft-like geometry to include the ethanol molecules. The two forms were not inter-convertible. The coordination polymer with 1,4-benzenedicarboxylate has a 2-dimensional structure with 2 × 2 grids having self-included urea that held DMF molecules by hydrogen bonds. [ABSTRACT FROM AUTHOR]

Through a room temperature reactant diffusion strategy, two coordination polymers [Zn(bpycz)Cl2]n (1) and [Zn(bpycz)Br2]n (2) were obtained from 3,6-bis(pyridin-3-yl)-9H-carbazole (bpycz) and the corresponding zinc halides. Single-crystal structural analysis revealed that the Zn(II) center suited a tetrahedral geometry in both 1 and 2, whereas the bpycz ligand adopted an anti,anti conformation in 1 but a syn,syn conformation in 2. As a result, coordination polymer 1 exhibited a wavelike chain structure with an arch bridge manner, whereas 2 also revealed a wavelike chain structure but with a sine wave manner. The differences in the ligand coordination mode and chain structure were most likely due to the influence of halide anions (Cl− in 1 and Br− in 2) with different sizes. X-ray powder diffraction (XRPD) proved that 1 and 2 were highly stable in H2O and various organic solvents, as well as over large pH ranges of 2–13 and 3–11, respectively, for 24 h. Thermogravimetric (TG) analysis confirmed that 1 and 2 have high thermal stability approaching 420 °C and 425 °C, respectively. Upon excitation, 1 and 2 emitted fluorescence at 420 and 412 nm, respectively, in the solid state and at 431 and 433 nm, respectively, in the suspension phase in water. The fluorescence of 2 dispersed in water could be obviously quenched by 4-aminobenzylamine (4-ABA) with a high quenching efficiency, excellent selectivity, and good sensitivity as well as a low limit of detection (LOD, 2.52 μM−1), indicating its potential as a fluorescence turn-off sensor material. Possible sensing mechanisms were explored, suggesting that the photoinduced electron-transfer process might be responsible for the quenching response. [ABSTRACT FROM AUTHOR]

It is attractive but challenging to develop a cocatalyst for CO2/cyclohexene oxide (CHO) copolymerization with a double metal cyanide (DMC) catalyst. In this study, we synthesized three coordination polymers (CPs) [Cd(3N3PY)(NDC)]·0.58H2O (1), [Zn(3N3PY)(IPA)]·3H2O (2) and [Cd(3N3PY)(NPA)]·2DMF·2H2O (3) (3N3PY = 4′-(4-(1H-1,2,4-triazol-1-yl)phenyl)-2,2′:6′,2′′-terpyridine, H2NDC = 2,6-naphthalene dicarboxylic acid, H2IPA = isophthalic acid, H2NPA = 2,2′-dinitro-4,4′-biphenyldicarboxylic acid). Crystal structural analyses show that 1–3 are different one-dimensional (1D) chains that further assemble into three-dimensional (3D) supramolecular structures by π–π and hydrogen bonding interactions. CPs 1–3 were applied as cocatalysts to assist DMC for CO2/CHO copolymerization and the efficient proportion of carbonate P–OC(O)O– in the product is 59% achieved for 2 at 80 °C in 1 MPa CO2. The proportion of carbonate F(CO2) and conversion rate of CHO (CCHO) are 63% and 93%, respectively. The mechanistic study on structure–activity relationship and chemoselectivity was performed. [ABSTRACT FROM AUTHOR]

The accurate and rapid detection of antibiotics and heavy-metal-based toxic oxo-anions in water media employing coordination polymers (CPs) as luminescent probes has attracted a lot of attention. Three new Cd(II)-based ternary CPs derived from first-presented L ligands, including [Cd(DCTP)(L)(OH)]n (1), [Cd(TBTA)(L)(OH)]n (2), and [Cd(NPHT)(L)(H2O)]n (3) (L = 2-((1H-imidazol-1-yl)methyl)-5,6-dimethyl-1H-benzo[d]imidazole, H2DCTP = 2,5-dichloroterephthalic acid, H2TBTA = tetrabromoterephthalic acid and H2NPHT = 3-nitrophthalic acid), were successfully assembled and characterized. 1 and 2 show 2D hcb layers, which can be further extended into a 3D supramolecular framework via classic hydrogen bonding interactions. 3 features a 1D double chain that ultimately spreads into a 2D network through weak hydrogen bonding interactions. With the advantages of high stability and excellent luminescent properties, the three CPs display high sensitivity, selectivity, and good anti-interference for the sensing of pefloxacin (PEF) and Cr2O72− ions (LOD values toward PEF: 3.82 × 10−7 mol L−1 for 1, 4.06 × 10−7 mol L−1 for 2, and 1.36 × 10−8 mol L−1 for 3, and toward Cr2O72− ions: 5.97 × 10−7 mol L−1 for 1, 5.87 × 10−7 mol L−1 for 2, and 8.21 × 10−8 mol L−1 for 3). These CPs are the first examples of bifunctional luminescent sensors to detect PEF and Cr2O72− in aqueous solutions. The luminescence quenching mechanisms are explored in detail. [ABSTRACT FROM AUTHOR]

The adjustment of crystal symmetry and intramolecular magnetic coupling is of great importance for the construction of high-performance single-molecule magnets. By using an aggregation-induced-emission-active pyridine-carbohydrazone-based Schiff base ligand and phosphine oxides, four dinuclear and one one-dimensional DyIII-based complexes, [Dy2(TPE-pc)2(Bu3PO)2Cl2]·2CH3CN·2H2O (1), [Dy2(TPE-pc)2(Cy3PO)2Cl2] (2), [Dy2(TPE-pc)2(MePA)2Cl2]·2CH3OH (3), [Dy2(TPE-pc)2(Ph3PO)2Cl2]2 (4) and [Dy2(TPE-pc)2(DPPO)Cl2]n (5) (H2TPE-pc = (E)-N′-(2-hydroxy-5-(1,2,2-triphenylvinyl)benzylidene)picolinohydrazide, MePA = N-phenyl-N′,N′′-bis(morpholinyl) phosphoric triamide, DPPO = piperazine-1,4-diylbis(diphenyl phosphine oxide)), were isolated. All complexes are made up of an enol oxygen-bridged Dy2 unit, where DyIII ions possess a pentagonal bipyramidal geometry with pseudo D5h symmetry. Magnetic measurements reveal that intramolecular DyIII–DyIII couplings are ferromagnetic and all complexes display a significant slow magnetic relaxation phenomenon below 30 K under a zero dc field. Ab initio calculations indicate that the anisotropic magnetic axes of all DyIII ions are approximately perpendicular to the higher-order symmetric axes in all complexes, and that DyIII–DyIII magnetic couplings along the magnetic axes effectively suppress the ground state quantum tunneling effect of magnetization and promote the occurrence of slow magnetic relaxation. Raman relaxation prevails in all complexes. In addition, the H2TPE-pc ligand shows an aggregation-induced emission (AIE) effect; however, all complexes exhibit an aggregation-caused quenching (ACQ) phenomenon. [ABSTRACT FROM AUTHOR]