Search

AbstractTwo new Cu(II)-based structures containing alternating chains and their magnetic properties are reported. Reaction of CuBr2 and 2-aminopyridine in methanol yielded [(2-aminopyridine)μ-Br(μ-OMe)Cu]n (1) which crystallizes in the triclinic space group P-1. Cu(II) ions are linked alternately by bibromide and bi-methoxide bridges into chains parallel to the a-axis. Reaction of copper perchlorate hexahydrate with 4-pyridone and pyrazine in methanol yielded [(μ-pz)(μ-κ-O-4-pyridone)2(μ-OH)2Cu2]n(ClO4)2n (2). The Cu(II) ions are alternately linked by bihydroxide and bi-κ-O-4-pyridone species parallel to the a-axis. Those chains are further linked by bridging pyrazine molecules ∼ parallel to the b-axis, with the pyrazine molecules and bi-hydroxide bridges alternating. The net effect is a rectangular lattice where each side of the rectangle is an alternating chain. The layers are separated by perchlorate ions. Both compounds are diamagnetic at room temperature. [ABSTRACT FROM AUTHOR]

Herein, the presented results show that previously studied DNA/RNA-interacting bis-imidazole-calix[4]arene systems can, in aqueous solutions, efficiently bind a series of biorelevant transition metal cations by coordination with the two imidazole arms at the small rim of their macrocyclic basket. The SCXRD and NMR results structurally characterised the complexes formed by referent bis-imidazole-calix[4]arene with Cu2+ and Zn2+. In solid-state (crystal), the bis-anilino derivative/Cu2+ complex, only upon exposure to the air, undergoes intramolecular dehydrogenative coupling of two neighbouring aniline units, yielding an azo bridge at the large rim of the calix[4]arene basket. In the biorelevant aqueous solution, the comparison of fluorometric titrations of referent calix[4]arene, with its analogues having one or two pyrene units grafted at the opposite (large) rim, revealed moderate-to-strong affinity towards transition metal cations, and, more importantly, a strong impact of pyrene on the binding affinity towards some cations. The pyrene arm(s) significantly diminished the affinity of the calix[4]arene-imidazole ligand towards Cu+ and strongly increased the affinity towards divalent Co2+ and Cd2+ cations. Moreover, the fluorometric response of some studied derivatives was strappingly sensitive to cation type. Since the counter-anion plays only a marginal role, such a change in selectivity is attributed to the intramolecular interaction of pyrene(s) with the calix[4]arene-imidazole system, sterically controlling the metal cation binding site. [ABSTRACT FROM AUTHOR]

Cyclic trinuclear homo-metal complexes, [{Fe(L3+2Br)py}3] (1) and [{Mn(L3+2Br)}3(py)2 MeOH] (2), along with a hetero-metal complex, [FeMn2(L3+2H)3(DMF)3] (3), were synthesized using asymmetric ditopic ligands (H3L3+2H: 2-(2-hydroxyphenyl)-6-ol-5-(salicylideneamino)benzoxazole, H3L3+2Br: 2-(2-hydrox-5-bromoyphenyl)-6-ol-5-(5-bromosalicylideneamino)benzoxazole). The molecular structure of 1 is characterized by a tripod structure with three-fold symmetry, where an enantiomer pair forms a dimeric capsule with dimensions of approximately 3 × 1.6 × 1.6 nm3. Complexes 2 and 3, which lack three-fold symmetry, exhibit similar molecular structures to previously reported complexes with these ligands, but do not form a capsule structure. Magnetic measurements of 1–3 reveal the presence of significantly weak antiferromagnetic interactions between the metal ions. [ABSTRACT FROM AUTHOR]

The reactivity of dppf-bridged triruthenium [Ru3(CO)10(µ-dppf)] with three thiourea derivatives namely N,N´-diisopropylthiourea, N,N´-dimethylthiourea and tetramethylthiourea has been examined. The reaction of [Ru3(CO)10(µ-dppf)] with N,N´-diisopropylthiourea or N,N´-dimethylthiourea affords [Ru3(CO)6{κ1-SC(NHR)2}(µ-dppf)(µ3-S)2] (1, R = CHMe2; 2, R = Me) that contains an intact thiourea ligand coordinated to a single ruthenium atom using the sulfur atom. The previously reported [Ru3(CO)7(µ-dppf)(µ3-S)2] (3) is also isolated as the minor product from the reaction with N, N´-dimethylthiourea. Both 1 and 2 furnishes 3 upon thermolysis in boiling toluene as confirmed by control experiments. In contrast, similar reaction between [Ru3(CO)10(µ-dppf)] and tetramethylthiourea furnishes [Ru3(CO)5(µ-CO){µ-η1,κ1-COPh}(µ-PhPFcPPh2)(µ3-S)] (4) and [HRu3(CO)7(µ-OH)(µ-dppf)(µ3-S)] (5) together with small amount of 3. All the new clusters are fluxional in solution which has been probed by VT NMR experiments and their molecular structures have been established by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Bergofungin D is a helical peptide of the peptaibol family consisting of 14 amino acids, six of which are the helix inducer aminoisobutyric acid (Aib). In the second third of the sequence, a hydroxyproline causes a bending of the helix and a disruption of the hydrogen bond network, and Aib7 is the only amino acid in this region involved in the hydrogen bond network. Therefore, modification of this residue can serve as a probe to monitor the effect of introducing amino acid substitutions on this more fragile helical turn. To validate this approach, we simplified the original bergofungin D by reducing the number of non‐classical amino acids, replacing the (R)‐isovaleric acid by its enantiomer or an Aib and the hydroxyproline with a proline, respectively, without affecting its secondary structure. Within the modified structure, we replaced Aib7‐Aib8 by its 1,2,3‐triazolodipeptide equivalent or Aib7 by a serine or a dehydrobutyrine. We have reported and analyzed five crystal structures, three of which are new, demonstrating the usefulness of the modified bergofungin D as a probe for monitoring the introduction of amino acid substitutions within a helical structure. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of new 1 'H -tetrazolo[1 ' ,5 ' - c ]-fused 3-aza-A- homosteroids were synthesized by azidation of progesterone, testosterone and hydrocortisone acetate in the presence of silicon tetrachloride. According to NMR spectroscopy and X-ray analysis, two double bond positional isomers (double bond in ring A or in ring B) are formed in various ratios; according to quantum chemical calculations, their energies are close within 0.4 kcal mol-1. Only low cytotoxic activity against Hep-2, MCF-7, HepG2, and Hek293 cell lines was determined in vitro for the compounds obtained. [ABSTRACT FROM AUTHOR]

Four new copper compounds of 2-amino-5-nitropyridine/pyridinium (5NAP/5NAPH) have been prepared and characterized: (5NAPH)2[CuBr4], 2; (d2-5NAPD)2[CuBr4], 2a; (5NAP)2CuCl2, 3; (5NAP)2CuBr2, 4. Compounds 2 and 2a are isomorphous and crystallize in the triclinic space group P-1. Packing is stabilized by hydrogen/deuterium bonds. Short Br...Br contacts provide potential magnetic superexchange pathways, but only very weak antiferromagnetic exchange is observed (J/kB∼-2 K). Compounds 3 and 4 are also isomorphous and crystallize in the monoclinic space group P21/c. The molecules are linked into chains by bihalide bridges, and the chains linked into rectangular/square layers by short X...X. contacts. Variable temperature magnetic data were best fit by the S = ½ antiferromagnetic rectangular model for 3 (C = 0.429(1) emu-K/mol-Oe, J/kB = −9.38(6) K, J'/kB = −5.91(4) K). Variable temperature magnetic susceptibility data for 4 were best fit by the two-dimensional antiferromagnetic square lattice model (C = 0.43(1) emu-K/mol-Oe, J/kB = −36.5(2) K). [ABSTRACT FROM AUTHOR]

The reaction of substituted acylthiourea derivatives (L1–L4) with [(PPh3)2Cu(μ‐Cl)2Cu(PPh3)] in a proper stoichiometric proportion gave the complexes (1–4) in good yields. The structures of the compounds (ligands and complexes) were advocated through spectroscopic analyses and x‐ray diffraction (XRD) studies; the latter confirmed their molecular structures. The complexes (1–4) were assessed for their cytotoxic potential through MTT assay against A549, T24, and HepG2 cancer cells, and their toxicity was evaluated using Vero and MCF‐10a normal cells. The complexes (1–4) displayed better cytotoxic action toward HepG2 cancer cells than cisplatin. Complexes 3 and 4 significantly destroyed A549 cancer cells with the IC50 values of 16.25 and 4.90 μM, respectively, which were lower than that of cisplatin (IC50 = 17.73 μM). Furthermore, the higher IC50 values in normal cells showed that the complexes were less hazardous to the normal cells except complex 3. The biocompatibility study showed that the complexes had minimal impact on normal human dermal fibroblast (NHDF) cells. The mode of cell death of complexes 3 and 4 against cancer cells was evaluated using staining assays. Both compounds demonstrated a significant reduction in live cells, an increase in early apoptotic cells, and pronounced proapoptotic effects, as evidenced by fragmented nuclei. Flow cytometry revealed a distinctive subpopulation in the subG0 phase, highlighting the compounds' ability to induce apoptosis and inhibit cell cycle progression. [ABSTRACT FROM AUTHOR]

As clinically used anticancer Pt(II) drugs have severe side effects, there is a growing interest for new metal complexes with great potential for cancer therapy. The current work aimed to prepare and characterize new Pd(II) and Pt(II) saccharinate (sac) complexes bearing pyridyl‐ and benzyldiphenylphosphines (PPh2Py and PPh2Bz, respectively), cis‐[Pd(sac)2(PPh2Py)2] (1), cis‐[PtCl(sac)(PPh2Py)2]·0.5DMF (2), cis‐[Pd(sac)2(PPh2Bz)2]·DMF (3) and trans‐[PtCl(sac)(PPh2Bz)2] (4) as promising anticancer and antiangiogenic drugs. The anticancer activity of the complexes was screened against seven cancer cell lines including HCT116 (colon), HepG2 (liver), MDA‐MB‐231 (breast), PANC‐1 (pancreatic), A549 (lung), C6 (glioma), DU145 (prostate) and normal human lung epithelial cells (BEAS‐2B). 1 and 2 did not show biological activity below 20 μM at 48 h, whereas 3 and 4 displayed significant cytotoxic effect on the cancer cells. 4 was the most potent complex (IC50 = 2.2–12.1 μM) and displayed much greater cytotoxicity than cisplatin in all the cancer cell lines. 4 caused apoptosis in HCT116 cells as evidenced by annexin V positivity and caspase 3/7 activity assays. Furthermore, the inhibition of antiapoptotic Bcl‐2 proteins by the complex suggested the intrinsic apoptosis. In addition, 4 greatly enhanced generation of intracellular reactive oxygen species (ROS) and consequently caused remarkable DNA double‐strand breaks in HCT116 cells. Moreover, the chick chorioallantoic membrane (CAM) assay was used to evaluate antiangiogenic potential of 4. The complex effectively inhibited angiogenesis at a dose of 50 ng, suggesting it as a promising multi‐targeted agent for antiangiogenic cancer treatment. [ABSTRACT FROM AUTHOR]

Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(L3+2R)}3] (1–3) with asymmetric multidentate linking ligands (H3L3+2R: R = H, Me, Br), were synthesized. The molecular structure of 1 is characterized as a tripod structure, with each V(V) ion coordinated by ONO-atoms from a tridentate Schiff base site and ON-atoms from a bidentate benzoxazole site of two respective H3L3+2H ligands. The intramolecular V⋯V distances range from 8.0683 to 8.1791 Å. Complex 4 is a mononuclear dioxidovanadium(V) complex, (Et3NH)[VO2(HL3+2H)]. Cyclic voltammograms of 1−3 in DMF revealed redox couples attributed to three single-electron transfer processes. [ABSTRACT FROM AUTHOR]

Catalytic activity and function of acetylcholinesterase (AChE; EC 3.1.1.7) have been recognized and studied for over a century and its quaternary and primary structures for about half a century, and its tertiary structure has been known for about 33 years. Clear understanding of relationships between the structure and the function is still pending for this enzyme. Hundreds of crystallographic, static snapshots of AChEs from different sources reveal largely one general backbone conformation with narrow entry into the active center gorge, tightly fit to accept one acetylcholine (ACh) molecule, in contrast to its high catalytic turnover. This short review of available X‐ray structures of AChEs from electric ray Torpedo californica, mouse and human, finds some limited, yet consistent deviations in conformations of selected secondary structure elements of AChE relevant for its function. The observed conformational diversity of the acyl pocket loop of AChE, unlike the large Ω‐loop, appears consistent with structurally dynamic INS data and solution‐based SAXS experiments to explain its dominant role in controlling the size of the active center gorge opening, as well as connectivity between the immediate surroundings of the buried active Ser, and catalytically relevant sites on the AChE surface. [ABSTRACT FROM AUTHOR]

Cyclic trinuclear homo-metal complexes, [{Fe(L3+2Br)py}3] (1) and [{Mn(L3+2Br)}3(py)2 MeOH] (2), along with a hetero-metal complex, [FeMn2(L3+2H)3(DMF)3] (3), were synthesized using asymmetric ditopic ligands (H3L3+2H: 2-(2-hydroxyphenyl)-6-ol-5-(salicylideneamino)benzoxazole, H3L3+2Br: 2-(2-hydrox-5-bromoyphenyl)-6-ol-5-(5-bromosalicylideneamino)benzoxazole). The molecular structure of 1 is characterized by a tripod structure with three-fold symmetry, where an enantiomer pair forms a dimeric capsule with dimensions of approximately 3 × 1.6 × 1.6 nm3. Complexes 2 and 3, which lack three-fold symmetry, exhibit similar molecular structures to previously reported complexes with these ligands, but do not form a capsule structure. Magnetic measurements of 1–3 reveal the presence of significantly weak antiferromagnetic interactions between the metal ions.

[(Z)-2′-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (5, L1) and [(Z)-4′-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (6, L2) were prepared, structurally characterized and used as ligands to obtain new metal complexes of types [MX(Ln)] [L1: M = Ag, X = OTf (7); M = Au, X = Cl (13); L2: M = Ag, X = OTf (8); M = Au, X = Cl (14)], [(MX)2(Ln)] [M = Ag, X = OTf, L1 (9); L2 (10)], [ZnCl2(Ln)] [L1 (15); L2 (16)] and [Ag(Ln)][PF6] [L1 (11); L2 (12)]. The silver complexes 7 and 8 were ionic species (1:1 electrolytes) in a MeCN solution, while in the solid state, the triflate fragments were bonded to the silver cations. Similarly, the 2:1 complexes 9 and 10 were found to behave as 1:2 electrolytes in a MeCN solution, but single-crystal X-ray diffraction demonstrated that compound 9 showed the formation of a dimer in the solid state: a tetranuclear [Ag(OTf)]4 built through bridging triflate ligands was coordinated by two bridging organoselenium ligands through the nitrogen from the oxazolone ring and the selenium atoms in a 1κN:2κSe fashion. Supramolecular architectures supported by intermolecular C−H∙∙∙π, C−H∙∙∙O, Cl∙∙∙H and F∙∙∙H interactions were observed in compounds 4, 5 and 9. The compounds exhibited similar photophysical properties, with a bathochromic shift in the UV-Vis spectra caused by the position of the oxazolone ring on the phenyl ring attached to the selenium atoms. [ABSTRACT FROM AUTHOR]

Recently, 5-[(4-ethoxyphenyl)imino]methyl-N-(4-fluorophenyl)-6-methyl-2-phenylpyrimidin-4-amine has been synthesized, characterized, and evaluated for its antibacterial activity against Enterococcus faecalis in combination with antineoplastic activity against gastric adenocarcinoma. In this study, new 5-iminomethylpyrimidine compounds were synthesized which differ in the substituent(s) of the aromatic ring attached to the imine group. The structures of newly obtained pyrimidine Schiff bases were established by spectroscopy techniques (ESI-MS, FTIR and 1H NMR). To extend the current knowledge about the features responsible for the biological activity of the new 5-iminomethylpyrimidine derivatives, low-temperature single-crystal X-ray analyses were carried out. For all studied crystals, intramolecular N–H∙∙∙N hydrogen bonds and intermolecular C–H∙∙∙F interactions were observed and seemed to play an essential role in the formation of the structures. Simultaneously, their biological properties based on their cytotoxic features were compared with the activities of the Schiff base (III) published previously. Moreover, computational investigations, such as ADME prediction analysis and molecular docking, were also performed on the most active new Schiff base (compound 4b). These results were compared with the highest active compound III. [ABSTRACT FROM AUTHOR]

Reaction of isoquinoline (iQuin) with cobalt(II) and nickel(II) chloride and bromide produced a family of neutral coordination complexes: (iQuin)2CoX2 [X = Cl (1), Br (2)], (iQuin)4CoX2 (X = Cl (3), X = Br (4)], (iQuin)4NiX2 [X = Cl, (5), X = Br, (6)], and (iQuin)2NiBr2(CH3CN)2 (7). The crystal structures of 1–5 and 7 are reported. The majority of the compounds crystallize with some of the iQuin ligands undergoing a ∼2-fold rotational disorder, likely caused by the nearly equivalent space occupied by the two positions. The disorder is temperature independent and ∼50:50 in all cases but one. Magnetic measurements for all seven compounds indicate that their behavior is dominated by single-ion anisotropy effects with indications of antiferromagnetic exchange also present in 1 and 2. [ABSTRACT FROM AUTHOR]

The new diprotic ligand 3,5-di-tert-butylsalicylaldehyde 4-ethyl-3-thiosemicarbazone, abbreviated H2(3,5-t-Bu2)-sal4eT, exists as the thio-keto tautomer and adopts the E-configuration with respect to the imine double bond, as evidenced by single-crystal X-ray analysis and corroborated by spectroscopic characterisation. Upon treatment with Cu(OAc)2·H2O in the presence of either 2,9-dimethyl-1,10-phenanthroline (2,9-Me2-phen) or 1,10-phenanthroline (phen) as a co-ligand in MeOH, this thiosemicarbazone undergoes conformational transformation (relative donor-atom orientations: syn,anti → syn,syn) concomitantly with tautomerisation and double deprotonation to afford the ternary copper(II) complexes [Cu{(3,5-t-Bu2)-sal4eT}(2,9-Me2-phen)] (1) and [Cu2{3,5-t-Bu2)-sal4eT}2(phen)] (2). Crystallographic elucidation has revealed that complex 1 is a centrosymmetric dimer of mononuclear copper(II) complex molecules brought about by intermolecular H-bonding. The coordination geometry at the copper(II) centre is best described as distorted square pyramidal in accordance with the trigonality index (τ = 0.14). The co-ligand adopts an axial–equatorial coordination mode; hence, there is a disparity between its two Cu–N coordinate bonds arising from weakening of the apical one as a consequence of the tetragonal distortion. The axial X-band ESR spectrum of complex 1 is consistent with retention of this structure in solution. Complex 2 is a centrosymmetric dimer of dinuclear copper(II) complex molecules exhibiting intermolecular H-bonding and π-π-stacking interactions. The two copper(II) centres, which are 4.8067(18) Å apart and bridged by the thio-enolate nitrogen of the quadridentate thiosemicarbazonate ligand, display two different coordination geometries, one distorted square planar (τ4 = 0.082) and the other distorted square pyramidal (τ5 = 0.33). Such dinuclear copper(II) thiosemicarbazone complexes, which are crystallographically characterised, are extremely rare. In vitro, complexes 1 and 2 outperform cisplatin as antiproliferative agents in terms of potency and selectivity towards HeLa and MCF-7 cancer cell lines. [ABSTRACT FROM AUTHOR]

Two new nickel(II) and cobalt(II) complexes, [Ni(MPAFA)3](BF4)2 (I) and [Co(MPAFA)3](BF4)2 (II) were synthesized from a pyrazole containing 'NN' bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine, (MPAFA) (L). The complexes I and II were characterized by various physico-chemical and spectral parameters. Both I and II were 1:3 (M:L) coordination complexes and behaving as 1:2 electrolytes. Single crystal X-ray diffraction studies revealed that both of them were distorted octahedral in nature with a N6 donor set. The binding interactions of the complexes with CT-DNA were studied by UV-Vis and fluorescence spectroscopic methods. I was found to bind with CT-DNA in a partial intercalative mode, whereas II bound via the groove-like manner in solutions. The ligand and the complexes were shown to have potential photocatalytic activity in degrading methylene-blue (MB) under UV-Vis light irradiation. [ABSTRACT FROM AUTHOR]

The Cu(II) complexes (H-5-FAP)2CuBr4 (1) and (H-2,3-dimpy)2CuCl4 (2) have been prepared and characterized structurally and magnetically (H-5-FAP = 2-amino-5-fluoropyridinium; H-2,3-dimpy = 2,3-dimethylpyridinium). They crystallize in the space groups P-1 and Pbcn, respectively, in comparison to their halido counterparts (H-5-FAP)2CuCl4 (1a) and (H-2,3-dimpy)2CuBr4 (2a) which crystallize in the space groups P21/c and P21/n. The differences in crystal packing, resulting in part from the difference in distortion of the CuX42− ions, create different magnetic lattices. Data for 1 were fit to the strong-rail ladder model resulting in a Curie constant of 0.400(8) emu-K/mol-Oe, J/kB-rail = −5.77(1) K and J/kB-rung = 3.17(3) K. Data for 2 were fit to the Curie-Weiss law resulting in a Curie constant of 0.398(1) emu-K/mol-Oe and θ = −0.11(4) K, indicating a virtual lack of magnetic exchange interactions. The structures and magnetic properties are compared to literature compounds and general trends noted. The differences in the chloride/bromide ions in the structure lead to significant differences in the packing in the cases of both 1 and 2, which result in differences in the antiferromagnetic exchange in both complexes and, in the case of 2, versus 2a, an elimination of the antiferromagnetic properties. [ABSTRACT FROM AUTHOR]

In order to probe the role of Li⋯F interactions toward the stabilisation of low-coordinate lithium complexes, the four fluoroarylsilylamides [LiN(SiMe3)(2-C6H4F)] (1-Li), [LiN(SiMe3)(2,6-C6H3F2)] (2-Li), [LiN(SiMe3)(C6F5)] (3-Li), and [LiN(SiMe2H)(2-C6H4F)] (4-Li) have been synthesised in high yields by deprotonation of the parent amines with nBuLi. They have been comprehensively characterised by multinuclear NMR spectroscopy, and complete assignments were achieved with the help of 2D NMR data. The molecular solid-state structures of [(2-Li)2]∞, [3-Li·Et 2 O]2, and [4-Li]8 were determined by single-crystal X-ray diffraction. They feature unusual coordination patterns, notably for the formation of the polymeric [(2-Li)2]∞ and a unique octagonal, crown-like [4-Li]8. In both structures, the role of Li⋯F non-covalent interactions was the key toward the building of the final architecture. It is shown that Li–F and C–F interatomic distances, along with |1 J C,F| coupling constants, can be used as qualitative tools for the evaluation of the presence and relative strength of Li⋯F contacts.

Saccharin (sacH) reacts with [Re2(CO)8(NCMe)2] at room temperature to afford dinuclear [Re2(CO)8(μ‐H)(μ‐sac‐κN,O)] (1), which contains a bridging sac ligand coordinated to both rhenium centers using the nitrogen and ketonic oxygen atoms, and the mononuclear compounds [Re(CO)5(sac‐κN)] (2) and cis‐[Re(CO)4(NCMe)(sac‐κN)] (3), both of which contain a sac ligand bonded to rhenium using only the nitrogen atom. Complex 3 that contains an MeCN ligand reacts with tri(2‐furyl)phosphine (PFu3) at room temperature to yield cis‐[Re(CO)4(PFu3)(sac‐κN)] (4). The molecular structures of 1–4 have been established by X‐ray crystallography, and the bonding in compound 1 has been examined by electronic structure calculations. [ABSTRACT FROM AUTHOR]

Two substituted phosphonium tetrahydoxidohexaoxidopentaborate(1-) salts, [iPrPPh3][B5O6(OH)4]·3.5H2O (1) and [MePPh3][B5O6(OH)4]·B(OH)3·0.5H2O (2), were prepared by templated self-assembly processes with good yields by crystallization from basic methanolic aqueous solutions primed with B(OH)3 and the appropriate phosphonium cation. Salts 1 and 2 were characterized by spectroscopic (NMR and IR) and thermal (TGA/DSC) analysis. Salts 1 and 2 were thermally decomposed in air at 800 °C to glassy solids via the anhydrous phosphonium polyborates that are formed at lower temperatures (<300 °C). BET analysis of the anhydrous and pyrolysed materials indicated they were non-porous with surface areas of 0.2–2.75 m2/g. Rhe recrystallization of 1 and 2 from aqueous solution afforded crystals suitable for single-crystal XRD analyses. The structure of 1 comprises alternating cationic/anionic layers with the H2O/pentaborate(1-) planes held together by H-bonds. The cationic planes have offset face-to-face (off) and vertex-to-face (vf) aromatic ring interactions with the iPr groups oriented towards the pentaborate(1-)/H2O layers. The anionic lattice in 2 is expanded by the inclusion of B(OH)3 molecules to accommodate the large cations; this results in the formation of a stacked pentaborate(1-)/B(OH)3 structure with channels occupied by the cations. The cations within the channels have vf, ef (edge-to-face), and off phenyl embraces. Both H-bonding and phenyl embrace interactions are important in stabilizing these two solid-state structures. [ABSTRACT FROM AUTHOR]

Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(L3+2R)}3] (1–3) with asymmetric multidentate linking ligands (H3L3+2R: R = H, Me, Br), were synthesized. The molecular structure of 1 is characterized as a tripod structure, with each V(V) ion coordinated by ONO-atoms from a tridentate Schiff base site and ON-atoms from a bidentate benzoxazole site of two respective H3L3+2H ligands. The intramolecular V⋯V distances range from 8.0683 to 8.1791 Å. Complex 4 is a mononuclear dioxidovanadium(V) complex, (Et3NH)[VO2(HL3+2H)]. Cyclic voltammograms of 1−3 in DMF revealed redox couples attributed to three single-electron transfer processes.

New hydroxy-methylenebisphosphonic derivatives were prepared with different P-functions. The outcome of the reaction of α-oxophosphonates (YC(O)P(O)(OR)2) and dialkyl phosphites or diarylphosphine oxides depended on the Y substituent of the oxo-compound, the nature of the P-reagent and the amount of the diethylamine catalyst. Starting from dimethyl α-oxoethylphosphonate, in the presence of 5% of diethylamine, the corresponding Pudovik adduct was the single product. While using 40% of the catalyst, the rearranged species with the >P(O)–O–CH–P(O)< skeleton was the exclusive component. A similar reaction of α-oxobenzylphosphonate followed the rearrangement protocol. X-ray crystallography revealed not only the spatial structures of the three products, but also an intricate pattern evolving from the interplay of slight chemical differences, solvent inclusion and disorder as well as H-bridge patterns, which invite further investigation. In vitro activity of the compounds was assessed on different tumor cell cultures using end-point-type cell tetrazolium-based measurements. These structure–activity studies revealed a cytostatic effect for four rearranged derivatives containing aromatic units. One of them had a pronounced effect on MDA-MB 231 and Ebc-1 cells, showing IC50 = 37.8 and 25.9 µM, respectively. [ABSTRACT FROM AUTHOR]

In drug discovery, protein kinase inhibitors (PKIs) are intensely investigated as drug candidates in different therapeutic areas. While ATP site-directed, non-covalent PKIs have long been a focal point in protein kinase (PK) drug discovery, in recent years, there has been increasing interest in allosteric PKIs (APKIs), which are expected to have high kinase selectivity. In addition, as compounds acting by covalent mechanisms experience a renaissance in drug discovery, there is also increasing interest in covalent PKIs (CPKIs). There are various reasons for this increasing interest such as the anticipated high potency, prolonged residence times compared to non-competitive PKIs, and other favorable pharmacokinetic properties. Due to the popularity of PKIs for therapeutic intervention, large numbers of PKIs and large volumes of activity data have accumulated in the public domain, providing a basis for large-scale computational analysis. We have systematically searched for CPKIs containing different reactive groups (warheads) and investigated their potency and promiscuity (multi-PK activity) on the basis of carefully curated activity data. For seven different warheads, sufficiently large numbers of CPKIs were available for detailed follow-up analysis. For only three warheads, the median potency of corresponding CPKIs was significantly higher than of non-covalent PKIs. However, for CKPIs with five of seven warheads, there was a significant increase in the median potency of at least 100-fold compared to PKI analogues without warheads. However, in the analysis of multi-PK activity, there was no general increase in the promiscuity of CPKIs compared to non-covalent PKIs. In addition, we have identified 29 new APKIs in X-ray structures of PK-PKI complexes. Among structurally characterized APKIs, 13 covalent APKIs in complexes with five PKs are currently available, enabling structure-based investigation of PK inhibition by covalent-allosteric mechanisms. [ABSTRACT FROM AUTHOR]

Herein, Cu (II), Zn (II), and Cd (II) complexes, [DEP(M)X2], encompassing the pyridine‐derived Schiff‐base ligand DEP, where DEP is (E)‐N,N‐diethyl‐2‐([pyridine‐2‐ylmethylene]amino)ethane‐1‐amine, are synthesized. X‐ray diffraction studies reveal distorted square pyramidal geometries for the Cd (II) and Cu (II) complexes, whereas the geometry of [DEP (Zn)Cl2] can best be described as trigonal bipyramidal. The antibacterial potential of DEP and its [DEP(M)X2] complexes were evaluated against four bacterial strains: Salmonella typhi, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa; five fungal strains: Candida glabrata, Candida albicans, Microsporum canis, Fusarium solani, and Aspergillus flavus; and Leishmania major protozoan. Complexes exhibited superior bactericidal, fungicidal, and leishmanicidal inhibition potential against all tested microbes compared with the free ligand. The preliminary cytotoxic activity of [DEP(M)X2] complexes on breast and colon carcinoma cells, that is, MCF‐7cell line and HCT‐116 cell line, respectively, revealed that studied complexes showed high cytotoxicity compared with ligand (DEP). Among the studied complexes, [DEP (Cd)Br2] exhibited an excellent inhibitory profile, as confirmed by the docking study. The molecular docking studies showed a good correlation between the biological activities of synthesized metal complexes and docking studies. We have confidence in the contribution of these complexes toward the design of new metal‐derived candidates that can treat infectious diseases. [ABSTRACT FROM AUTHOR]

The antipsychotic drug Olanzapine was crystallized with aromatic acid, 2,5-dihydroxybenzoic acid in isopropyl alcohol by slow evaporation which led to the formation of olanzapinium 2,5-dihydroxybenzoate crystalline salt. The structure of the compound was characterized by 1H-NMR, 13C-NMR, and single-crystal X-ray diffraction analysis. The Hirshfeld analyses were performed to quantify the order and nature of intermolecular interactions in the crystal network. Employing computational approaches, the compound was tested for its affinity against antipsychotic activity by molecular docking and molecular dynamic simulation to attest the conformational stability over time step of 100 ns. Besides, bioactivity and ADMET properties were also predicted to ratify the result. The compound asserted neither carcinogenic nor mutagenic activity and has high oral bioavailability. Hence, this synthesized novel compound Olanzapinium 2,5-dihydroxybenzoate recognized in the study possesses high potential as an effective antipsychotic compound, and can further be examined for its efficiency by in vivo studies. The synthesized compound was submitted to NCBI PubChem database using accession substance ID: 441329256. The crystal structure was submitted to CCDC (Cambridge Crystallographic Data Centre) with submission ID: 2010899.

[Os3(CO)10(NCMe)2] reacts with pyrrolidine in refluxing benzene to give the known clusters [HOs3(CO)10(µ,κ1-NCH2CH2CH2CH2)] (1) and [HOs3(CO)10(µ,η1,κ1-C=NCH2CH2CH2)] (2), in addition to the new triosmium cluster [HOs3(CO)9(µ,κ2-N=C(CH3)C=NCH2CH2CH2)] (5), whose ancillary heterocyclic ligand is formed by C–C coupling involving the nitrile carbon of NCCH3 and the α-carbon of pyrrolidine. Refluxing 2 in n-octane furnishes the known µ3-imidoyl cluster [HOs3(CO)9(µ3,η1,κ1-C=NCH2CH2CH2)] (4) along with the new pentaosmium cluster [H3Os5(CO)14(µ,η1,κ1-C=NCH2CH2CH2)] (6) which exhibits a metallic core based on an edge-bridged tetrahedron. The doubly metalated pyrrolidine ligand ligates one of the apical osmium atoms in the Os4 tetrahedron and the bridging Os(CO)3 moiety in 6. The bonding in clusters 5 and 6 has been investigated by electronic structure calculations. [ABSTRACT FROM AUTHOR]

[Os3(CO)10(NCMe)2] reacts with pyrrolidine in refluxing benzene to give the known clusters [HOs3(CO)10(µ,κ1-NCH2CH2CH2CH2)] (1) and [HOs3(CO)10(µ,η1,κ1-C=NCH2CH2CH2)] (2), in addition to the new triosmium cluster [HOs3(CO)9(µ,κ2-N=C(CH3)C=NCH2CH2CH2)] (5), whose ancillary heterocyclic ligand is formed by C–C coupling involving the nitrile carbon of NCCH3 and the α-carbon of pyrrolidine. Refluxing 2 in n-octane furnishes the known µ3-imidoyl cluster [HOs3(CO)9(µ3,η1,κ1-C=NCH2CH2CH2)] (4) along with the new pentaosmium cluster [H3Os5(CO)14(µ,η1,κ1-C=NCH2CH2CH2)] (6) which exhibits a metallic core based on an edge-bridged tetrahedron. The doubly metalated pyrrolidine ligand ligates one of the apical osmium atoms in the Os4 tetrahedron and the bridging Os(CO)3 moiety in 6. The bonding in clusters 5 and 6 has been investigated by electronic structure calculations. [ABSTRACT FROM AUTHOR]

Three new tripod tetradentate phenolate-amines (H2L1, H2L4 and H2L9), together with seven more already related published ligands, were synthesized, and characterized. With these ligands, two new dinuclear doubly-bridged-phenoxido copper(II) complexes (3, 4), and six more complexes (1, 2, 5–8), a new trinuclear complex (9) with an alternative doubly-bridged-phenoxido and –methoxido, as well as the 1D polymer (10) were synthesized, and their molecular structures were characterized by spectroscopic methods and X-ray single crystal crystallography. The Cu(II) centers in these complexes exhibit distorted square-pyramidal arrangement in 1–4, mixed square pyramidal and square planar in 5, 6, and 9, and distorted octahedral (5+1) arrangements in 7 and 8. The temperature dependence magnetic susceptibility study over the temperature range 2–300 K revealed moderate–relatively strong antiferromagnetic coupling (AF) (|J| = 289–145 cm−1) in complexes 1–6, weak-moderate AF (|J| = 59 cm−1) in the trinuclear complex 9, but weak AF interactions (|J| = 3.6 & 4.6 cm−1) were obtained in 7 and 8. No correlation was found between the exchange coupling J and the geometrical structural parameters of the four-membered Cu2O2 rings. [ABSTRACT FROM AUTHOR]

The tetranuclear iron(III) compounds [Fe4(μ3-O)2(μ-LZ)4] (1–3) were obtained by reaction of FeCl3 with the shortened salen-type N2O2 tetradentate Schiff bases N,N'-bis(salicylidene)-o-Z-phenylmethanediamine H2LZ (Z = NO2, Cl and OMe, respectively), where the one-carbon bridge between the two iminic nitrogen donor atoms guide preferentially to the formation of oligonuclear species, and the ortho position of the substituent Z on the central phenyl ring selectively drives towards Fe4 bis-oxido clusters. All compounds show a flat almost-symmetric butterfly-like conformation of the {Fe4(μ3-O)2} core, surrounded by the four Schiff base ligands, as depicted by both the X-ray molecular structures of 1 and 2 and the optimized geometries of all derivatives as obtained by UM06/6-311G(d) DFT calculations. The strength of the antiferromagnetic exchange coupling constants between the iron(III) ions varies among the three derivatives, despite their magnetic cores remain structurally almost unvaried, as well as the coordination of the metal ions, with a distorted octahedral environment for the two-body iron ions, Feb, and a pentacoordination with trigonal bipyramidal geometry for the two-wing iron ions, Few. The different magnetic behavior within the series of examined compounds may be ascribed to the influence of the electronic features of Z on the electron density distribution (EDD) of the central {Fe4(μ3-O)2} core, substantiated by a Quantum Theory of Atoms In Molecules (QTAIM) topological analysis of the EDD, as obtained by UM06 calculations 1–3. [ABSTRACT FROM AUTHOR]

[(Z)-2′-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (5, L1) and [(Z)-4′-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (6, L2) were prepared, structurally characterized and used as ligands to obtain new metal complexes of types [MX(Ln)] [L1: M = Ag, X = OTf (7); M = Au, X = Cl (13); L2: M = Ag, X = OTf (8); M = Au, X = Cl (14)], [(MX)2(Ln)] [M = Ag, X = OTf, L1 (9); L2 (10)], [ZnCl2(Ln)] [L1 (15); L2 (16)] and [Ag(Ln)][PF6] [L1 (11); L2 (12)]. The silver complexes 7 and 8 were ionic species (1:1 electrolytes) in a MeCN solution, while in the solid state, the triflate fragments were bonded to the silver cations. Similarly, the 2:1 complexes 9 and 10 were found to behave as 1:2 electrolytes in a MeCN solution, but single-crystal X-ray diffraction demonstrated that compound 9 showed the formation of a dimer in the solid state: a tetranuclear [Ag(OTf)]4 built through bridging triflate ligands was coordinated by two bridging organoselenium ligands through the nitrogen from the oxazolone ring and the selenium atoms in a 1κN:2κSe fashion. Supramolecular architectures supported by intermolecular C−H∙∙∙π, C−H∙∙∙O, Cl∙∙∙H and F∙∙∙H interactions were observed in compounds 4, 5 and 9. The compounds exhibited similar photophysical properties, with a bathochromic shift in the UV-Vis spectra caused by the position of the oxazolone ring on the phenyl ring attached to the selenium atoms.

Recently, 5-[(4-ethoxyphenyl)imino]methyl-N-(4-fluorophenyl)-6-methyl-2-phenylpyrimidin-4-amine has been synthesized, characterized, and evaluated for its antibacterial activity against Enterococcus faecalis in combination with antineoplastic activity against gastric adenocarcinoma. In this study, new 5-iminomethylpyrimidine compounds were synthesized which differ in the substituent(s) of the aromatic ring attached to the imine group. The structures of newly obtained pyrimidine Schiff bases were established by spectroscopy techniques (ESI-MS, FTIR and 1H NMR). To extend the current knowledge about the features responsible for the biological activity of the new 5-iminomethylpyrimidine derivatives, low-temperature single-crystal X-ray analyses were carried out. For all studied crystals, intramolecular N–H∙∙∙N hydrogen bonds and intermolecular C–H∙∙∙F interactions were observed and seemed to play an essential role in the formation of the structures. Simultaneously, their biological properties based on their cytotoxic features were compared with the activities of the Schiff base (III) published previously. Moreover, computational investigations, such as ADME prediction analysis and molecular docking, were also performed on the most active new Schiff base (compound 4b). These results were compared with the highest active compound III.

The new diprotic ligand 3,5-di-tert-butylsalicylaldehyde 4-ethyl-3-thiosemicarbazone, abbreviated H2(3,5-t-Bu2)-sal4eT, exists as the thio-keto tautomer and adopts the E-configuration with respect to the imine double bond, as evidenced by single-crystal X-ray analysis and corroborated by spectroscopic characterisation. Upon treatment with Cu(OAc)2·H2O in the presence of either 2,9-dimethyl-1,10-phenanthroline (2,9-Me2-phen) or 1,10-phenanthroline (phen) as a co-ligand in MeOH, this thiosemicarbazone undergoes conformational transformation (relative donor-atom orientations: syn,anti → syn,syn) concomitantly with tautomerisation and double deprotonation to afford the ternary copper(II) complexes [Cu{(3,5-t-Bu2)-sal4eT}(2,9-Me2-phen)] (1) and [Cu2{3,5-t-Bu2)-sal4eT}2(phen)] (2). Crystallographic elucidation has revealed that complex 1 is a centrosymmetric dimer of mononuclear copper(II) complex molecules brought about by intermolecular H-bonding. The coordination geometry at the copper(II) centre is best described as distorted square pyramidal in accordance with the trigonality index (τ = 0.14). The co-ligand adopts an axial–equatorial coordination mode; hence, there is a disparity between its two Cu–N coordinate bonds arising from weakening of the apical one as a consequence of the tetragonal distortion. The axial X-band ESR spectrum of complex 1 is consistent with retention of this structure in solution. Complex 2 is a centrosymmetric dimer of dinuclear copper(II) complex molecules exhibiting intermolecular H-bonding and π-π-stacking interactions. The two copper(II) centres, which are 4.8067(18) Å apart and bridged by the thio-enolate nitrogen of the quadridentate thiosemicarbazonate ligand, display two different coordination geometries, one distorted square planar (τ4 = 0.082) and the other distorted square pyramidal (τ5 = 0.33). Such dinuclear copper(II) thiosemicarbazone complexes, which are crystallographically characterised, are extremely rare. In vitro, complexes 1 and 2 outperform cisplatin as antiproliferative agents in terms of potency and selectivity towards HeLa and MCF-7 cancer cell lines.

It has been proposed that late transition metals with low coordination numbers (square planar or linear) can act as nucleophiles and participate in σ-hole interactions as electron donors. This is due to the existence, in this type of metal complexes, of a pair of electrons located at high energy d-orbitals (dz2 or dx2-y2), which are adequate for interacting with antibonding σ-orbitals [σ*(X–Y)] where Y is usually an electron withdrawing element and X an element of the p-block. This type of d[M]→σ*(X–Y) interaction has been reported for metals of groups 9–11 in oxidation states +1 and +2 (d8 and d10) as electron donors and σ-holes located in halogen and chalcogen atoms as electron acceptors. To our knowledge, it has not been described for σ-holes located in pnictogen atoms. In this manuscript, evidence for the existence of pnictogen bonding involving the square planar Pt(II) metal as the electron donor and Sb as the electron acceptor is provided by using an X-ray structure retrieved from the Cambridge Structural Database (CSD) and theoretical calculations. In particular, the quantum theory of atoms in molecules (QTAIM), the noncovalent interaction plot (NCIPlot) and molecular electrostatic potential (MEP) methods were used. Moreover, to further confirm the nature of the Sb···Pt(II) contact, a recently developed method was used where the electron density (ED) and electrostatic potential (ESP) distribution were compared along the Sb···Pt(II) bond path. [ABSTRACT FROM AUTHOR]

The PDZ domains are modular domains that recognise short linear C-terminal sequences in proteins that organise the formation of complex multi-component assemblies. We have crystallised the third PDZ domain of the neuronal postsynaptic density-95 protein (PSD95-PDZ3) at mildly acidic pH conditions and obtained up to four polymorphs. Thus, below pH 4.0, the protein crystallised into prism-shaped crystals that belonged to the trigonal space group P3112. In contrast, above this pH value, the crystals' shape changes to long needles belonging to the monoclinic P21 and two different orthorhombic packings of the P212121 space group. In addition, all the polymorphs share the main crystallographic interface, where the sidechain of the Asp332 imitates the binding of the C-terminal moiety to the canonical binding motif. Furthermore, we have analysed how changes in the ionisation state of some specific residues might be critical for crystallising the different polymorphs. The analysis of these polymorphs provides clues on the relevance of specific protein-protein interactions in protein crystallisation. However, these structures allow dissecting those electrostatic interactions that play a role in the conformation adopted by some residues and the extra-domain components upon binding C-terminal sequences. [ABSTRACT FROM AUTHOR]

The chalcogen bond has been recently defined by the IUPAC as the attractive noncovalent interaction between any element of group 16 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. Commonly used chalcogen bond donor molecules are divalent selenium and tellurium derivatives that exhibit two σ-holes. In fact, the presence of two σ-hole confers to the chalcogen bonding additional possibilities with respect to the halogen bond, the most abundant σ-hole interaction. In this manuscript, we demonstrate that selenoxides are good candidates to be used as σ-hole donor molecules. Such molecules have not been analyzed before as chalcogen bond donors, as far as our knowledge extends. The σ-hole opposite to the Se=O bond is adequate for establishing strong and directional ChBs, as demonstrated herein using the Cambridge structural database (CSD) and density functional theory (DFT) calculations. Moreover, the effect of the metal coordination of the selenoxide to transition metals on the strength of the ChB interaction has been analyzed theoretically. The existence of the ChBs has been further supported by the quantum theory of atoms in molecules (QTAIM) and the noncovalent interaction plot (NCIPlot). [ABSTRACT FROM AUTHOR]

The new homodinuclear complexes of the general formula [Ln2L3(NO3)3] (where HL is newly synthesized 2-((2-(benzoxazol-2-yl)-2-methylhydrazono)methyl)phenol and Ln = Sm3+ (1), Eu3+ (2), Tb3+ (3a, 3b), Dy3+ (4), Ho3+ (5), Er3+ (6), Tm3+ (7), Yb3+ (8)), have been synthesized from the lanthanide(III) nitrates with the polydentate hydrazone Schiff base ligand. The flexibility of this unsymmetrical Schiff base ligand containing N2O binding moiety, attractive for lanthanide metal ions, allowed for a self-assembly of these complexes. The compounds were characterized by spectroscopic data (ESI-MS, IR, UV/Vis, luminescence) and by the X-ray structure determination of the single crystals, all of which appeared to be different solvents. The analytical data suggested 2:3 metal:ligand stoichiometry in these complexes, and this was further confirmed by the structural results. The metal cations are nine-coordinated, by nitrogen and oxygen donor atoms. The complexes are two-centered, with three oxygen atoms in bridging positions. There are two types of structures, differing by the sources of terminal (non-bridging) coordination centers (group A: two ligands, one nitro anion/one ligand, two nitro anions, group B: three ligands, three anions). [ABSTRACT FROM AUTHOR]

The antipsychotic drug Olanzapine was crystallized with aromatic acid, 2,5-dihydroxybenzoic acid in isopropyl alcohol by slow evaporation which led to the formation of olanzapinium 2,5-dihydroxybenzoate crystalline salt. The structure of the compound was characterized by 1H-NMR, 13C-NMR, and single-crystal X-ray diffraction analysis. The Hirshfeld analyses were performed to quantify the order and nature of intermolecular interactions in the crystal network. Employing computational approaches, the compound was tested for its affinity against antipsychotic activity by molecular docking and molecular dynamic simulation to attest the conformational stability over time step of 100 ns. Besides, bioactivity and ADMET properties were also predicted to ratify the result. The compound asserted neither carcinogenic nor mutagenic activity and has high oral bioavailability. Hence, this synthesized novel compound Olanzapinium 2,5-dihydroxybenzoate recognized in the study possesses high potential as an effective antipsychotic compound, and can further be examined for its efficiency by in vivo studies. The synthesized compound was submitted to NCBI PubChem database using accession substance ID: 441329256. The crystal structure was submitted to CCDC (Cambridge Crystallographic Data Centre) with submission ID: 2010899. [ABSTRACT FROM AUTHOR]

Two new coordination polymers (CPs), [Ni 2 (dip) 2 (obb) 2 ]⋅2H 2 O, and [Cd 2 (dip) 2 (obb) 2 (H 2 O)]⋅5.5H 2 O, were successfully synthesized via hydrothermal processes utilizing the organic linkers 4,4 ′ -oxybisbenzoate (obb) and 2,6-di(1 H -imidazole-1-yl)pyridine (dip). The unique structures of both CPs were confirmed by single-crystal X-ray diffraction studies. Ni-CP presents an intricate three-fold interpenetrated 3D framework, featuring a rare cag topology centered around dinuclear nodes. In contrast, Cd-CP exhibits a distinctive non-interpenetrated 2D framework with an unusual kIa topology. Despite Cd-CP's water coordination and the inclusion of substantial guest water molecules, it unexpectedly exhibited lower proton conductivity than Ni-CP, which is non-porous and contains much less water content. Synthesis and characterization of novel coordination polymers (CPs), Ni 2 (dip) 2 (obb)2·2H 2 O and Cd 2 (dip) 2 (obb) 2 (H 2 O)·5.5H 2 O, reveal intricate 3D and distinctive 2D frameworks. Cd-CP shows lower proton conductivity despite higher water content, offering insights into structure-property relationships in proton-conducting CPs. [Display omitted] • Synthesis of two new coordination polymers using unique organic linkers. • Confirmation of their structures via single-crystal X-ray diffraction studies. • Ni-CP: intricate 3D framework with rare cag topology; Cd-CP: distinctive 2D framework. • Surprising observation: Cd-CP exhibits lower proton conductivity despite higher water content. • Ni-CP shows a good proton conductivity of 1.15 × 10−3 S cm−1. [ABSTRACT FROM AUTHOR]

New tetranuclear ruthenium carbonyl cluster Ru 4 (CO) 9 (µ-CO){µ 4 -η2-P(CH 2) 3 PPh 2 }(µ 4 -η4-C 6 H 4) has been obtained from thermolysis reaction of Ru 3 (CO) 10 (µ-dppp) in octane. The compound was analysed by spectroscopic method and single crystal X-ray diffraction. The bonding properties were further elucidated via topological analysis study. [Display omitted] The reaction of Ru 3 (CO) 12 and dppp [dppp = 1,3-bis(diphenylphosphino)propane/Ph 2 P(CH 2) 3 PPh 2 ] in the presence of benzophenone ketyl radical anion afforded [Ru 3 (CO) 11 ] 2 (µ-dppp) (1) Ru 3 (CO) 10 (µ-dppp) (2), Ru 3 (CO) 9 (µ-dppp)(ƞ1-dppp) (3) and Ru 3 (CO) 8 (µ-dppp) 2 (4). Refluxing 2 in octane yields new triruthenium clusters Ru 3 (CO) 9 (μ 3 -PPh(CH 2) 3 PPh(C 6 H 4)) (5) and Ru 4 (CO) 9 (µ-CO){µ 4 -η2-P(CH 2) 3 PPh 2 }(µ 4 -η4-C 6 H 4) (6), as a result of C H and C P bond activation involving the Ph 2 P(CH 2) 3 PPh 2 ligand. Compounds 2 and 6 have been structurally determined by the single crystal X-ray diffraction. As expected, the Ph 2 PCH 2 CH 2 CH 2 PPh 2 ligand in 2 is equatorially bonded to Ru–Ru bond in µ 2 -η2 mode. In contrast, the X-ray structure of 6 shows an µ 4 -η2-PCH 2 CH 2 CH 2 PPh 2 and a benzyne group coordinated to a square of Ru atoms. A rotation of benzyne group on a square of Ru atoms was supported by variable temperature NMR studies. The topological analysis was performed on 6 to further elucidate their chemical bond properties. [ABSTRACT FROM AUTHOR]

Ordered supramolecular hydrogels assembled by modified aromatic amino acids often exhibit low mechanical rigidity. Aiming to stabilize the hydrogel and understand the impact of conformational freedom and hydrophobicity on the self‐assembly process, two building blocks based on 9‐fluorenyl‐methoxycarbonyl‐phenylalanine (Fmoc‐Phe) gelator which contain two extra methylene units in the backbone, generating Fmoc‐γPhe and Fmoc‐(3‐hydroxy)‐γPhe are designed. Fmoc‐γPhe spontaneously assembled in aqueous media forming a hydrogel with exceptional mechanical and thermal stability. Moreover, Fmoc‐(3‐hydroxy)‐γPhe, with an extra backbone hydroxyl group decreasing its hydrophobicity while maintaining some molecular flexibility, self‐assembled into a transient fibrillar hydrogel, that later formed microcrystalline aggregates through a phase transition. Molecular dynamics simulations and single crystal X‐ray analyses reveal the mechanism underlying the two residues' distinct self‐assembly behaviors. Finally, Fmoc‐γPhe and Fmoc‐(3‐OH)‐γPhe co‐assembly to form a supramolecular hydrogel with notable mechanical properties are demonstrated. It has been believed that the understanding of the structure‐assembly relationship will enable the design of new functional amino acid‐based hydrogels. [ABSTRACT FROM AUTHOR]

The term matere bond has been recently used to refer to an attractive noncovalent interaction between any element of group 7 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. The utilization of metals such as σ-hole donors is starting to attract the attention of the scientific community. In this manuscript, a comparison between matere bonds and well-known σ-hole interactions (halogen and chalcogen bonds) is carried out using three X-ray structures, retrieved from the Cambridge structural database (CSD), and density functional theory calculations (DFT). The novelty of this work resides in the utilization of a neutral Re(VII) system as the matere bond donor and multivalent chalcogen and halogen donors. In fact, as far as our knowledge extends, the description of σ-hole interactions in Se(VI) is unprecedented in the literature. The σ-hole interactions in Re(VII), Se(VI) and Cl(VII) electron acceptors are analyzed and compared using several computational tools. [ABSTRACT FROM AUTHOR]

A phenylazo appended ortho‐vanillin Schiff base scaffold (HAZ) has been used for selective colorimetric sensing of Cu2+ in semi‐aqueous medium (methanol–water, 1:1, v/v) in the presence of 16 cations and 20 anions, and the limit of detection is 1.8 × 10−7 M. The structures of HAZ and Cu (II) complex, [Cu(AZ)2], have been characterised by spectroscopic data (UV–Vis, Fourier transform infrared and electron paramagnetic resonance) and established by the single crystal X‐ray diffraction measurement. The Job's plot from the absorption studies has also confirmed the 1:2 stoichiometry of Cu2+:HAZ. The absorption spectrum of [Cu (AZ)2] has returned to the spectrum of HAZ on the addition of Na2EDTA solution which is again recovered upon the addition of Cu2+ solution. Discrete Fourier transform computations were carried out using the coordinates of the X‐ray structures of the compounds, and the molecular functions were used to correlate the solution spectroscopic properties. In addition to this, the probe is treated on MDA‐MB 231 breast cancer cells to check the cytotoxicity. The probe is used for the detection of trace quantity of Cu2+ in the cancer cell. [ABSTRACT FROM AUTHOR]

The metalloligand approach was used to obtain a novel CuII/ZnII heterobimetallic coordination polymer (CP) 1, based on the carefully designed bispidine ligand L4. CP 1, characterized by single crystal (SC‐) and powder X‐ray diffraction methods (P‐XRD), is constituted by repeating large 32‐membered macrocycles forming ribbon‐like linear arrays and it features a CuII‐coordination site occupied by a markedly labile MeCN. We also describe the synthesis and characterization of intermediate metalloligands (with CuII, FeIII, MnII, and PdII, the latter three obtained as SCs and characterized accordingly) and provide a view of potential intermediate species along the route from metalloligands to heterometallic CPs. [ABSTRACT FROM AUTHOR]

Reaction of two equivalents of the bulky 1,3-bis(2,6-diethylphenyl)thiourea ligand (L) with MX (being M = Cu+, Ag+; and X = Cl−, Br−, I−) in acetonitrile afforded neutral complexes of the type [MXL2] [CuClL2].2CH3CN (1a); [CuBrL2].2CH3CN (1b); [CuIL2] (1c): [AgClL2] (2a); [AgBrL2] (2b) and [AgIL2] (2c). The two aromatic groups in free ligand were found to be trans with respect to the thiourea unit, which was a reason to link the ligand molecules via intermolecular hydrogen bonding. Intramolecular hydrogen bonding was observed in all metal complexes. The copper complexes 1a and 1b are acetonitrile solvated and show not only intra- but also intermolecular hydrogen bonding between the coordinated thiourea and the solvated acetonitrile molecules. Silver complexes reported here are the first examples of structurally characterized tricoordinated thiourea-stabilized monomeric silver(I) halides. Molecular docking studies were carried out to analyze the binding modes of the metal complexes inside the active site of the human insulin (HI) protein. Analysis of the docked conformations revealed that the electrostatic and aromatic interactions of the protein N-terminal residues (i.e., Phe and His) may assist in anchoring and stabilizing the metal complexes inside the active site. According to the results of docking studies, the silver complexes exhibited the strongest inhibitory capability against the HI protein, which possesses a deactivating group, directly bonded to silver. All compounds were fully characterized by elemental analysis, NMR spectroscopy, and molecular structures of the ligand, and five out of six metal complexes were also confirmed by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Keywords: 2,5-dihydroxy-1,4-quinone; cyclic voltammetry; phoshine; phosphinyl; X-ray structures EN 2,5-dihydroxy-1,4-quinone cyclic voltammetry phoshine phosphinyl X-ray structures 531 541 11 07/18/22 20220701 NES 220701 1 Introduction Coordination complexes built around the structural motif of 2,5-bis(phosphine) I p i -hydroquinone are relatively rare. SP 31 sp P NMR (C SB 6 sb D SB 6 sb ): I i = 73.3 (s). 4.3.4 Syntheses of 2,5-bis(diphenylphosphinyl)-3,6-hydroquinone (4a) and 2,5-bis(diisopropylp... Both compounds were synthesized by the same procedure, thus a detailed description of only one of them ( B 4a b ) is provided. Reported herein are syntheses and investigations for two of such compounds, 2,5-bis(diphenylphosphinyl)-3,6-dihydroxy-quinone ( B 4a b ) and 2,5-bis(diisopropylphosphinyl)-3,6-dihydroxy-quinone ( B 4b b ) (Figure 2). Thus, crystals of 2,5-dihydroxy-1,4-quinone and 2,5-dihydroxy 3,6-dichloro-1,4-quinone contain I intermolecular i hydrogen bonding between hydroxy groups and oxygens of quinone functionalities [[28]]. [Extracted from the article]

The semihemiporphyrazines are a class of ligands comprised of a heterocycle ring and an isoindoline unit linked through a bridging nitrogen atom. These bidentate ligands can be altered in the exocyclic heteroatom position on the isoindoline and in the identity of the heterocycle. Herein, we present a series of Re(CO)3X (X=Cl, Br, py) complexes of indazole and pyrazole‐based semihemiporphyrazines. Changing the ligand and the axial position at the metal alters the character of the complexes, including the structure, tautomerization and charge of the chelate. Modifications to the semihemiporphyrazine also alter the electronic structure of the resultant Re(CO)3 complexed as demonstrated in their UV‐visible spectra. In addition to full characterization, we carried out density functional theory (DFT) and time‐dependent density functional theory (TDDFT) to interrogate the electronic structures of these compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four coordination polymers constructed from flexible bis-pyridyl-bis-amide (boba) and tetracarboxylic acid are reported. • Rare structures are observed for these coordination polymers. • The metal effect on the structural diversity of the CPs supported by the 1,2,4,5-BETC4- is subject to the change of the flexibility of the bpba ligand. Reactions of N ‚ N' -bis(3-methylpyridyl)oxalamide (L1), N ‚ N' -bis(3-methylpyridyl)adipoamide (L2) or N ‚ N' -bis(3-methylpyridyl)sebaamide (L3) with 1,2,4,5-benzenetetracarboxylic acid (1,2,4,5-H 4 BETC) and metal salt yield four coordination polymers: {[Cu 2 (L1) 2 (1,2,4,5-BTEC)(H 2 O)]·5H 2 O} n , 1 , [Cu 2 (L2)(1,2,4,5-BTEC)(H 2 O) 4 ] n , 2 , [Cu 2 (L3)(1,2,4,5-BTEC)(H 2 O) 4 ] n , 3 , and [Ni(L2)(1,2,4,5-BTEC) 0.5 (H 2 O) 2 ] n , 4. These polymers have been structurally characterized using single crystal X-ray crystallography. Complex 1 forms a 3D framework adopting a new (4.62) 2 (42.62.82)(42.64.84) 2 (63.83) topology, whereas the others display 2D layers with the bex topology for 2 and 3 , and a rare 4,4L88 topology for 4. The structural diversity of these coordination polymers is influenced by the combined effects of metal identity and ligand flexibility, supported by the 1,2,4,5-BTEC4- ligand. Their thermal properties have also been investigated. [ABSTRACT FROM AUTHOR]

• 1,3-Diiminoisoindolines undergo ring expansion upon exposure to hydrazine to afford 1,4-diaminophthalazines. • Unsubstituted 1,4-diaminophthalazine reacts with rhenium carbonyl halides to produce dimeric Re(CO)3 complexes. • Pyrazole and indazole-modified 1,4-diaminophthalazines bind to Re(CO)3 in a fashion analogous to similarly structured diimines, but lack visible metal-to-ligand charge transfer (MLCT) bands in the visible region of the spectrum. 1,3-Diiminoisoindolines and substituted variants react with hydrazine to produce 1,4-diaminophthalazines. In this paper, we present the chemistry of 1,4-diaminophthalazine and two modified versions with the Re (CO) 3 unit. The 1,4-diaminophthalazine ligand forms a bimetallic complex similar to that seen with unmodified phthalazine. In contrast, the semihemiporphyrazine-derived chelating ligands bind Re (CO) 3 as neutral bidentate compounds; the freebase pyrazole and indazole modified 1,4-diaminophthalazines exhibit multiple tautomerization states with ionizable protons. Notably, protonation of the meso bridging nitrogen atom reduces the degree of conjugation between the two halves of the chelate, resulting in a diimine-like complex that lacks significant absorption in the visible spectrum due to the abrogation of the low energy metal to ligand charge transfer (MLCT) transition. [Display omitted] [ABSTRACT FROM AUTHOR]

Driven by the great potential of solar energy conversion this study comprises the evaluation and comparison of two different design approaches for the improvement of copper based photosensitizers. In particular, the distinction between the effects of a covalently linked and a directly fused naphthalimide unit was assessed. For this purpose, the two heteroleptic Cu(I) complexes CuNIphen (NIphen = 5-(1,8-naphthalimide)-1,10-phenanthroline) and Cubiipo (biipo = 16H-benzo-[4′,5′]-isoquinolino-[2′,1′,:1,2]-imidazo-[4,5-f]-[1,10]-phenanthroline-16-one) were prepared and compared with the novel unsubstituted reference compound Cuphen (phen = 1,10-phenanthroline). Beside a comprehensive structural characterization, including two-dimensional nuclear magnetic resonance spectroscopy and X-ray analysis, a combination of electrochemistry, steady-state and time-resolved spectroscopy was used to determine the electrochemical and photophysical properties in detail. The nature of the excited states was further examined by (time-dependent) density functional theory (TD-DFT) calculations. It was found that CuNIphen exhibits a greatly enhanced absorption in the visible and a strong dependency of the excited state lifetimes on the chosen solvent. For example, the lifetime of CuNIphen extends from 0.37 µs in CH2Cl2 to 19.24 µs in MeCN, while it decreases from 128.39 to 2.6 µs in Cubiipo. Furthermore, CuNIphen has an exceptional photostability, allowing for an efficient and repetitive production of singlet oxygen with quantum yields of about 32%.