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Triggering the spin-state switching (SSS) in solutions at room temperature (RT) has attracted attention in the field of molecular switches. Herein, we report the preparation and switching properties of a ferrous complex Fe(H2Bpz2)2(L -C2H5) (H2Bpz2 = dihydrobis(1-pyrazolyl)borate, L -C2H5 = (4,15-bis[4-(N,N-diethylamino)phenyl][1,2,5]thiadiazolo-[3,4-i]dipyrido[a,c]phenazine)). Upon near-infrared (NIR) laser on, the ferrous complex formed H-aggregation in the solution with enhanced ligand-to-ligand charge transfer, which thus achieved a high-spin state. Upon switching the NIR laser off, the ferrous complex changed to J-aggregation with enhanced intramolecular charge transfer, which resulted in the low-spin state; as a consequence, charge transfer triggered reversible SSS in the solution at RT. More interestingly, further confinement into the solid-state three-dimensional polymer sponge did not affect the SSS performance of the ferrous complex, suggesting the high potential of Fe(H2Bpz2)2(L -C2H5) for practical applications in future molecular electronic and spintronic devices. [ABSTRACT FROM AUTHOR]

Iron(II)-triazole coordination polymers have attracted considerable interest for their synthetic versatility, which allows tuning their spin-crossover (SCO) properties. Embedding SCO solid particles in sponge matrices is a simple, powerful, and generic approach to construct processable SCO materials. Here, we have studied a series of magnetic frameworks based on partial ligand substitution by using different chemical mixtures of two organic ligands, yielding four isostructural coordination polymers. The integration of the hygroscopic SCO material has endowed the composite sponge with the ability to capture moisture under ambient conditions. In particular, not only does a spin-crossover transition during absorption occur, but also a color variation has been achieved by varying humidity. The consequences of cooperativity and the exposed surface of the composite sponge on the spin transition were evaluated and the most promising materials among them were screened. This work provides guiding significance for the fabrication and practical application of spin-crossover-sponge materials. [ABSTRACT FROM AUTHOR]

Converting Cr(VI) to Cr(III) and subsequent precipitation of Cr(III) represents an efficient approach for wastewater treatment. Although it is possible to eliminate Cr(III) by adjusting the pH to elicit precipitation, this method is expensive and can lead to secondary pollution. Herein, we report a composite (C-S-U) composed of calcium silicate hydrate (C-S-H) and UiO-66-NH2 nanoparticles (UN NPs). We demonstrated a remarkable synergistic effect for the purification of total chromium concentration (Cr(T)) attributed to the affinity of Cr(III) to C-S-H, coupled with the Cr(III) sorption-enhanced photocatalysis. C-S-U exhibited a significantly enhanced photocatalytic rate (0.052 min−1) for Cr(VI) but also delivered outstanding sorption capacity (217.9 mg g−1) towards Cr(III). Cr(T) could be reduced to an ultra-low level (∼0.007 mg L−1) within 90 min. Meanwhile, regeneration of Cr(III)-passivated C-S-U and Cr recollection was achieved. Electrochemical analysis and X-ray photoelectron spectroscopy were undertaken to reveal the mechanism of removal. [ABSTRACT FROM AUTHOR]

Metal–organic framework nanosheets (MONs) are expected to turn the cornerstone of integrated electronic and optoelectronic devices owing to their unique properties. However, as the premise and guarantee for research applications, adjustable preparation and accurate control of MONs remain a challenge. Here in this work, we demonstrate that the sizes and colors of MONs can be tuned by subtle control of the solution pH (from 3 to 11) during the precursor preparation. Where the variation of the sizes of MONs from nano-scale (lateral size smaller than 200 nm) to micro-scale (lateral size larger than 10 μm) was achieved, which was accompanied by the continuous color variation from green to gray for the solid-state samples, and from orange to pink for the colloidal suspensions. As a result, linear correlations between the sizes and colors of the MONs with the solution pH were established. Laser irradiation experiments further demonstrated the inverse relationship between the fluorescence intensity of MONs and the pH, providing a fairly good strategy for the controlled preparation and color adjustment of MONs. [ABSTRACT FROM AUTHOR]

Photoreversible color‐switching materials, which can reversibly change color in response to external light stimuli, have attracted increasing attention for their applications in time‐sensitive information storage and optical data storage fields. But most of the related materials are dyes or redox compounds with ultraviolet as the light source, dramatically limiting the cycling stability during discoloration processes. To address this problem, a near‐infrared (NIR)‐responsive rewritable paper via doping layered Co‐metal–organic frameworks (MOFs) into the stable polyvinylidene fluoride matrix is reported for the first time. Layered Co‐MOF shows a rapid color‐switching characteristic between orange and black blue upon NIR illumination on/off because of the interlayer spacing changes. Benefiting from the soft network structures of the matrix, Co‐MOF can be homogeneously distributed to deliver an outstanding reversibility performance, including rapid response, coloration in a short period, and decoloration within about 3 min in ambient air. The fabrication of new photoreversible color switching system holds great potential in communication security, which offers a viable pathway to achieve ink‐free photoreversible printing. [ABSTRACT FROM AUTHOR]

Efficient atmospheric water harvesting has been a focal point in the broad spectrum of water collection sources, to alleviate the challenges caused by water shortage. Herein, we report a systematic approach focused on preparing a polymer hydrophobic–hydrophilic gel, doped with super hygroscopic materials (SHMs), enabling high moisture capture, color response, and in situ moisture storage. The hybrid gel quickly achieves a water uptake of 100% under different humidity levels from 43% to 98%. The hybrid gel achieves not only the capture of moisture but also the response of an obvious color change from blue to pink, visible to the naked eye. The interesting properties of the hybrid gel give rise to a wide range of possibilities in design and engineering for humidity capture response and detection application, providing bright prospects for the next generation of atmospheric water harvesting systems. [ABSTRACT FROM AUTHOR]

Humidity visualization is of significant importance across both the living systems and the industrial processes, which remains a huge challenge. Herein, for the first time, a hydrophilic sponge, which is composed of rigid gel and super hygroscopic material, has been demonstrated capable of all‐weather humidity visualization in a portable, convenient, economical, and in situ manner. This promising aspect is attributed to the effective all‐weather humidity capture and various color display as a response to the humidity capture capacity, of the super hygroscopic material; as well as the rapid humidity transport and excellent humidity storage ability provided by the porous rigid gel. As a consequence, combined with a smartphone, the invisible information on the environment's relative humidity levels, on the one hand, can be correlated qualitatively with the specific color display of the sponge; on the other hand, it can be correlated quantitatively with the specific color intensity, providing a pretty good smart model for humidity visualization in various complex environments. The present humidity visualization technology may open up a new avenue for the development of novel humidity sensors with a wide range of practical applications. [ABSTRACT FROM AUTHOR]

The practical application of molecular switches is highly dependent on the reversible spin-state switching under ambient conditions, which needs a delicate materials design. Here, by confining a spin-crossover material into a sponge, the challenging goal of reversible spin-state switching in the solid state under ambient conditions has been realized, upon irradiation with a 980 nm laser for 120 s followed by shutting off the laser for 150 s. More importantly, further integration of the hygroscopic material has endowed the sponge with the merits of effective atmospheric humidity-triggered reversible spin-state switching under ambient conditions for the first time, accompanied by a reversible color variation upon naturally occurring humidity capture/release cycles. This work is expected to provide a fairly good strategy for developing novel molecular switches triggered by natural energy sources at the device level. [ABSTRACT FROM AUTHOR]

By using in-site generated formate, 2D HOFs of TCPP, with excellent stability and permanent porosity (BET surface area larger than 560 m2 g−1), have been obtained. The constructed 2D square-like TCPP-HCO2 grid sheets have shown considerable in-plane stability that comparable to the TCPP-based 2D MOFs, that can be exfoliated into atomically thin 2D nanosheets with efficient photocatalytic activity in aqueous system. These results are expected to shed light on the application-orientated one-pot synthesis for new kinds of multi-dimensional HOFs. [ABSTRACT FROM AUTHOR]

Precise revealing the mechanisms of excited‐state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)‐4‐(((4H‐1,2,4‐triazol‐4‐yl)imino)methyl)‐2,6‐dimethoxyphenol (TIMDP) adopting a D‐π‐A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4–H2O–OH(TIMDP)–N(TIMDP) hydrogen‐bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g. UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen‐bonding bridge, resulting in crystals of [HTIMDP]+⋅[H2O]⋅[ClO4]−. As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D‐π‐A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters. [ABSTRACT FROM AUTHOR]

Combining the advantages of ultrathin two-dimensional (2D) nanosheets featuring stimuli-responsive properties with lanthanide-doped upconverting nanoparticles (UCNPs) represents a challenging goal in near infrared (NIR) light-triggered molecular switching under ambient conditions. Here, we present the fabrication of a 2D@UCNPs hybrid system comprising the integration of distinct features of atomically thin 2D spin-crossover nanosheets ({[Fe(1,3-bpp)2(SCN)2]2}n) and ytterbium ion (Yb3+)-sensitized hexagonal phase UCNPs [sodium yttrium fluoride (NaYF4): 20 mol% Yb3+, 1 mol% erbium ions (Er3+)]. The UCNPs are hybridized with 2D nanosheets involving bare thiocyanate (SCN−) ligands on both sides of the basal surfaces of the nanosheets, and as a consequence, effective synergistic effects between the up-conversion luminescence (UCL) and spin-state interconversion were established. Upon NIR (980 nm) irradiation, the UCL weakened the metal-to-ligand charge-transfer (MLCT) and triggered high-spin (HS) to low-spin (LS) state transition. Upon subsequent heating (40 °C), the MLCT strengthened and the LS to HS state transition was achieved, suggesting a reversible molecular-switching had occurred which was triggered by altering NIR and thermal stimuli. In addition, the corresponding aqueous colloidal suspension is highly stable, nontoxic, environmentally and human friendly in nature, making it suitable for practical applications in photo-switching devices and fabrication of next-generation user-friendly and wearable, fashionable optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this work, two new single crystals of copper-tetraphenylporphine (Cu-TPP) (crystals 2 and 3), which were induced by external magnetic fields with strengths of 0.5 and 0.8 T, respectively, have been prepared and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. Compared with the original Cu-TPP (crystal 1), crystals 2 and 3 exhibit significant differences in their unit cell parameters, crystalline stacking styles and intermolecular interactions, resulting in a “compressed” crystal packing. Here, the number of closer interactions (H…H, C…H/H…C) increased with the magnetic field strength, accompanied by a decrease in the number of π…π (C…C) interactions as a sacrifice. On considering the results of our previous work, the results here suggest that a magnetic field has a different influence on the crystallization process of mono-component and multi-component materials, which will certainly provide some suggestions for the design of crystallization strategies for other materials with the presence of an external magnetic field. [ABSTRACT FROM AUTHOR]

In order to determine the effect of halogen bonding on supramolecular assemblies and photophysical properties of diaryl oxalates, diaryl oxalate itself and its derivatives with fluorine, chlorine, bromine, and iodine substituents in the p-position of phenyl rings were studied and compared. Their single-crystal structures were studied by geometrical analysis and theoretical calculation. The study reveals that different halogen bonds are formed with respect to different halogen atoms, such as C...F and X...X (bromine and iodine atoms) interactions, and molecular stacking modes would be affected by halogen bonds directly. Comparative studies of photophysical properties in dilute solution and solid state indicate that halogen substitutions would not affect the emission processes of diaryl oxalates in dilute solution; this is not the case for their solid state. This work has demonstrated that halogen bonds play an important role in regulating structures and photophysical properties of diaryl oxalates. [ABSTRACT FROM AUTHOR]

An investigation into the effect of switching methoxy and hydroxyl groups on molecular salts is presented in this study. The salts HL1+·NO3− (1), L1·HL1+·ClO4− (2), L1·HL1+·H2PO4−·H2O (3), HL2+·NO3− (4), HL2+·ClO4− (5) and HL2+·H2PO4− (6) were synthesized and structurally characterized. The study was carried out by analyzing the crystal structure, properties and intermolecular interactions within each of the salts using IR and fluorescence spectra, TGA, Hirshfeld surface analyses and π…π stacking motifs. Salt 1 has a layered structure, while 4 has a distorted 3-D structure. Salt 2 possesses an edge-to-face type plane interaction, while 5 is formed with a twisted structure. It is important to note that water molecules play a key role in the 1-D chain structure of salt 3. The π…π stacking motif of salts 1–3 have a herringbone structure, while salts 3–6 exhibit a γ-structure. In addition, the competitive crystallization of the synthetic salts was investigated and found to be consistent with the measured solubility. [ABSTRACT FROM AUTHOR]

Abstract: Fabricating of melamine (MM)‐based multi‐component functional self‐assemblies have been investigated intensively. However, studies on protonated MM still in its infancy. Hence in this work, we studied the self‐assembly of protonated MM in different forms (1⋅ClO4− [MMH+⋅ClO4−⋅H2O], 2⋅Br− [MMH2+⋅2Br−⋅H2O], and 3⋅Cl− [MMH2+⋅2Cl−⋅H2O]) with various oxoanions (SO42−, NO3− and PO43−). Results revealed that the original anions ClO4‐, Br‐, and Cl‐, though not included in these self‐assemblies, are mainly responsible for the spectacular morphologies, from cuboids (1.SO42−) to prismoids (2.SO42−), sheets (3.SO42−), fibers (1.NO3−), rods (2.NO3−, 3.NO3−) and ribbons (1.PO43−, 2.PO43−, 3.PO43−). The crystalline phase and compositions of these self‐assemblies were found to be independent from the original protonated MM and the degree of protonation, while depend on the specific oxoanions. Therefore, the self‐assembly mechanism can be proposed. These results may provide an effective strategy for morphological control, especially for further development in protonated MM‐based functional materials. [ABSTRACT FROM AUTHOR]

By using the ligands 4-(4-bromobenzylideneamino)-4H-1,2,4-triazole (L1) and 4-(4-iodobenzylideneamino)-4H-1,2,4-triazole (L2), four different organic salts HL1+·Cl− (1), L1·HL1+·ClO4− (2), HL2+·Cl− (3), and L2·HL2+·ClO4− (4) have been synthesized and structurally characterized through single-crystal X-ray diffraction (L1, L2, 2 and 3) and PXRD (1 and 4) measurements. The results revealed that ligands L1 and L2 themselves exhibit a polymeric 1-D chain in a zigzag structure connected by C–Br…N and C–I…N halogen-bonding contacts, respectively. L1 in salt 2 was connected into a 3-D structure through N–H…O hydrogen-bonding contacts, while the interleaved 3-D network of L2 in salt 3 was mainly connected by C–I…Cl halogen-bonding contacts. As a result, the fluorescence properties of ligands L1 and L2 were reserved in halogen-bonding connected salts 1 and 3, while there was a reduction in hydrogen-bonding connected salts 2 and 4. Thus, the relationship between emission properties and halogen-bonding contacts can be proposed. [ABSTRACT FROM AUTHOR]

In this study, the potential of oxoanion separation with the ligands N-4-methylbenzyl-4-amino-1,2,4-triazole (L1), N-4-fluorobenzyl-4-amino-1,2,4-triazole (L2), N-4-hydroxy benzyl-4-amino-1,2,4-triazole (L3), and N-3-methoxy-4-hydroxybenzyl-4-amino-1,2,4-triazole (L4) was explored. The salts of sulphate, nitrate, and perchlorate were crystallized in the form of [HL1]+[HSO4]−·H2O, [HL2]+[HSO4]−·H2O, 2[HL3]+[SO4]2−·2(H2O), and 2[HL4]+[SO4]2−·H2O, [HL3]+[NO3]−·H2O and [HL4]+[NO3]−, and [HL3]+[ClO4]− and [HL4]+[ClO4]−, respectively. Competitive crystallization and competitive sulphate-binding experiments demonstrated special recognition of the sulphate–water clusters (in the forms of [HSO4−·H2O]n or [SO42−·H2O]n) via the parallel packed 3-D architectures of HL1+, HL2+, and HL4+ cations, which were far more effective and selective than the non-3-D structure of HL3+ cation. The observed selectivity for sulphate, nitrate, and perchlorate was found to be anti-Hofmeister. In addition, the selective separation of sulphate anions in seawater was investigated, which demonstrated the real-world application of the present strategy. [ABSTRACT FROM AUTHOR]

Because of the differences in the position and degree of fluorine substitution, four fluorinated DSA (9,10-distyrylanthracene) derivatives, namely 9,10-bis(4-fluorostyryl)anthracene (4-BFSA), 9,10-bis(3-fluorostyryl)anthracene (3-BFSA), 9,10-bis(3,5-difluorostyryl)anthracene (BDFSA) and 9,10-bis(3,4,5-trifluorostyryl)anthracene (BTFSA), display different crystal packing and photophysical properties in the solid state. Furthermore, the photophysical properties in solution have been investigated. The results show that all the four compounds exhibit tunable aggregation-induced enhanced emission (AIEE) properties. Notably, DSA, 4-BFSA, 3-BFSA and BDFSA display solvatochromic properties. The relationship between their structures and photophysical properties was further discussed. This work has demonstrated that depending on the amount and position, fluorine substitution can tune the structures and photophysical properties of DSA effectively. [ABSTRACT FROM AUTHOR]

Two complexes 1 [Cu(L1)2(H2O)2]·2H2O and 2 [Co(L2)2 (H2O)4]·4H2O formed by hetero N- and O-donor ligands 1-methyl-3-imidazole-4-carboxylic acid (L1H) and 2-methyl-5-pyridine carboxylic acid (L2H) have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. These two complexes consist of a 2:1 ratio of ligand to metal ion. The analysis of Hirshfeld surfaces and crystal structures reveal that O‒H···O hydrogen bond interactions and C‒H···π intermolecular interactions support the three-dimensional supramolecular structures of complexes 1 and 2. Meanwhile, the coordinated water molecules and lattice water molecules play a key role in the construction of their crystal structures. [ABSTRACT FROM AUTHOR]

Three diaryl oxalate derivatives, bis(4-chlorophenyl)oxalate, bis(2, 6-dichlorophenyl)oxalate and bis(2, 4, 6-trichlorophenyl)oxalate, have been synthesized and characterized via X-ray single crystal diffraction, differential scanning calorimetry, thermogravimetric analysis and infrared spectra, for the purpose of studying the influence of chlorine substitution on the crystal structures of diaryl oxalate. This work has demonstrated that, depending on the position and number, chlorine substitution will influence the molecular geometries and stacking modes of diaryl oxalate by tuning the types and numbers of intermolecular interactions. [ABSTRACT FROM AUTHOR]

The co-crystallization of a benzimidazole derivative ( 1, CHNO, 3-[[[2-[[(4-Cyanophenyl) amino]methyl]-1-methyl-1H-benzimidazol-5-yl]carbonyl]pyridin-2-ylamino]propionic acid ethyl ester), with fumaric acid (FA) and maleic acid (MA), has been performed. The FA and MA molecules, both are connected with two molecules of CHNO, giving birth to a three-components compound ( 1·0.5FA, CHNO) and a four-components compound ( 1·MA, CHNO). Single-crystal X-ray diffractions show that the three different planar moieties (4-cyanophenyl, benzimidazol, and pyridin-2-yl) in compound CHNO display ' cis-form' conformation ( a) in the crystal of 1, while exhibiting 'intermediate-state' conformation ( b) and ' trans-form' conformation ( c) in compounds 1·0.5FA and 1·MA, respectively. Hirshfeld surfaces analysis, DFT calculations, DSC measurements, IR and Raman spectroscopy were performed, which revealed that the thermal stability of the three conformations follows the order c > b > a. [ABSTRACT FROM AUTHOR]

Two new mononuclear iron (II) coordination complexes: Fe(L1)2(SCN)2(1, L1:5-dimethylether-4-(4-methylphenyl)-3-(2-pyridinyl)-1,2,4-triazole) and Fe(L2)3(ClO4)2(2, L2:1-ethyl acetate-2-(2-pyridinyl)-imidazole), for the exploration of spin-crossover compounds have been synthesized and characterized. Structural analysis revealed that the framework of complex1is featured with 1-D chain structure connected by weak π···π interactions between the adjacent L1ligands, while complex2featured with various kinds of weak intermolecular hydrogen bonding interactions between Fe(L2)32+cation and ClO4−anion, which lead to a close crystal packing. The intermolecular interactions have shown a significant influence on the physical properties, and magnetic measurements of complexes1and2in the solid state at the room temperature revealed that the weak intermolecular interactions in1resulted in HS (high-spin) state, while the strong interactions in2lead to LS (low-spin) state over the whole temperature range. [ABSTRACT FROM PUBLISHER]

Nano-scale materials are acquiring a leading role in the fabrication of new generation devices, especially for the practical application of molecular bi-stability. However, the preparation of purely bi-stable nano-objects without the use of surfactants/polymers remains a challenging task. Here, we present a new approach to prepare spin-crossover (SCO) vesicular nano-spheres with single-external diameters of approximately 100 nm using a CHCl3–H2O mixture. The nano-spheres are based on a series SCO complexes, [Fe(H2Bpz2)2(dialkyl-bipy)] (H2Bpz2 = dihydrobis(1-pyrazolyl)borate, dialkyl-bipy = N4,N4′-dialkyl-(2,2′-bipyridine)-4,4′-dicarbo-xamide, alkyl = propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and cetyl), and are prepared through a self-assembly process that is similar to liposomal assembly, with the dialkyl-bipy moiety acting as the hydrophobic tail and the Fe(H2Bpz2) moiety acting as the hydrophilic head. This study reveals that the alkyl chain length plays a key role in the formation of these nano-spheres and the determination of their spin transition temperatures. The spin transition temperatures for the bulk materials are centered at around 160 K, and show a positive correlation with the alkyl chain length. Meanwhile, for the vesicular nano-spheres in the solid state, their transition temperatures are above room-temperature, and the correlation with the alkyl chain length is negative. These results provide an effective strategy for the design of new metal–organic materials for nano-technological applications. [ABSTRACT FROM AUTHOR]

The compound {[Zn(μ-dicyanamide)(pyrazinamide)](pyrazinamide)} has been synthesized and further characterized by elemental analysis, single-crystal X-ray diffraction, and thermogravimetric analysis. Structural analysis revealed that the dicyanamide anion acted as bridging ligand in a μ-1,5 mode, resulting a polymeric 1-D chain structure. The pairwise N3-H3B···N1 and N9-H9B···N7, N3-H3A···O2 and N9-H9A···O1, N3-H3B···N7 and N9-H9B···N1 multiple hydrogen bonding interactions, impart enhanced stability to supramolecular structures. Hirshfeld surfaces and fingerprint plots were applied to arrive at the same conclusion, which is stabilised mainly by H-H, N-H, O-H interactions. DNA binding studies showed that the compound had interacted with DNA. [ABSTRACT FROM AUTHOR]

A series of Fe(II) complexes with (ClO4)−(SeCN)−, (ClO4)−(SCN)−, (Fe2OCl6)2−, and 2(BF4)−counter-anions for complexes1–4, derived from dmbpy (4,4′-dimethyl-2,2′-bipyridine), were prepared. The single-crystal studies and the Hirshfeld surfaces analysis revealed that the (Fe2OCl6)2−anion results more distortional octahedral geometry of the cation than other anions. In particular, the (ClO4)−(SCN)−and (Fe2OCl6)2−anions lead to complexes2and3stabilized via C-H···π interactions and π···π interactions, which were not found in the other two complexes. However, the double-chain structure of complex4was formed by C-H···F and C-H···C hydrogen bonds interactions. Due to the influence of different anions, magnetic susceptibility measurements showed that complex1was in high-spin (HS) state and complex2was in low-spin (LS) state. [ABSTRACT FROM PUBLISHER]

Single crystals of compound L (CHN): 4-(2-benzimidazole)-1,2,4-triazole and its hydrate were obtained via slow evaporation. The structures of the crystals were characterized by IR, TGA/DSC and X-ray diffraction analysis. Molecules in crystal 1 are linked by a combination of N-H···N and C-H···N hydrogen bonds into 2D layers, and further stacked into a 3D structure by π··· π stacking interactions. Compared to crystal 1, the water molecules play a key role in the construction of the crystal structure of hydrate 2. The 2D layers were formed via O-H···N, O-H···O, N-H···N hydrogen bonds, and further stacked by O-H···O hydrogen bonds and π··· π stacking interactions in crystal 2. A detailed analysis of the intermolecular interactions and crystal packing via Hirshfeld surface analysis and fingerprint plots reveals that the structures are stabilized mainly by N···H/H···N, C···H/H···C hydrogen bonds, H···H weak interactions and π··· π stacking interactions. [ABSTRACT FROM AUTHOR]

Four novel lanthanide compounds based on the 4-(4-carboxyphenyl)-1,2,4-triazole ligand (Hcpt), {[Pr2(cpt)4(H2O)10]·10H2O·2ClO4} (1), {[Ln(cpt)2(H2O)2(OH)]·4H2O}n (Ln = Er(2), Lu(3)), and {[Sm(cpt)2(CH3CH2OH)(H2O)3]·ClO4}n (4), have been obtained under hydrothermal conditions and further characterized by elemental analysis, single-crystal X-ray diffraction and thermogravimetric analysis. Compound 1 exhibits a discrete dinuclear structure constructed by one cpt− ligand coordinated to two Pr3+ ions and another cpt− ligand coordinated to more than one Pr3+ ion. Compounds 2 and 3 are isomorphous and every cpt− ligand coordinates to two Ln3+ ions, resulting in a polymeric 1-D chain structure. Different from the above compounds, the nitrogen atoms of triazole are also involved in the coordination of compound 4. One cpt− ligand coordinates to two Sm3+ ions and another cpt− ligand coordinates to more than one Sm3+ ion, meanwhile, the nitrogen atoms of triazole coordinate to the third Sm3+ ion, resulting in a 2-D polymeric network structure. The luminescence properties of compound 4 were characterized, and the results revealed that it exhibited characteristic Sm3+ emission in the yellow region. [ABSTRACT FROM AUTHOR]

2,3-Dimethylpyrazine and 1,2-bis(4-pyridyl)ethane are both N-containing aromatic heterocyclics with two N atoms approximately in the para position. We here report two compounds derived from these heterocyclics (compounds 1 and 2). Compounds 1 and 2 both form a 1:1 2,3-dimethylpyrazine:perchloric acid (PA) and 1,2-bis(4-pyridyl)ethane:PA cocrystal, respectively. Their crystal structures were characterized by single-crystal X-ray diffraction, which revealed that the C-H⋯O and N-H⋯O hydrogen bonding interactions were found to stabilize the crystal structure in compounds 1 and 2. However, PA plays a necessary role for the one-dimensional structure in 1 and the three-dimensional structure in 2. Hirshfeld surfaces and fingerprint plots were applied to get the same conclusion. [ABSTRACT FROM AUTHOR]

Four DSA (9,10-distyrylanthracene) derivatives, namely 9,10-bis(4-fluorostyryl)anthracene (BFSA), 9,10-bis(4-chlorostyryl)anthracene (BCSA), 9,10-bis(4-bromostyryl)anthracene (BBSA) and 9,10-bis(4-iodostyryl)anthracene (BISA) have been synthesized and characterized via single crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, photoluminescence spectroscopy, ultraviolet-visible absorption spectroscopy, solid fluorescence quantum yield measurement and other techniques, for the purpose of studying the influence of halogen atoms on the structures and photophysical properties of 9,10-distyrylanthracene. The results indicate that the introduction of halogen atoms into DSA significantly influences the molecular geometries and stacking modes in the crystals. The photophysical properties in solution and in the crystalline state of the five compounds were comparatively investigated, and the relationship between the crystalline state emissions and crystal structures was further discussed. This work has demonstrated that the introduction of halogen atoms into DSA could influence the molecular packing and molecular geometries in the crystals and endow them with different photophysical properties. [ABSTRACT FROM AUTHOR]

The quantitative visualizations and comparisons between the four pyrazinamide (PZA) polymorphs (α, β, γ and δ) have been investigated by graphical tools based on three-dimensional Hirshfeld surfaces and two-dimensional fingerprint plots. The comparisons were performed in terms of crystal structure, d, Shape index, Curvedness and d surfaces, and fingerprint plots. The results revealed that the α and γ forms featured with 1D chains and the π···π stacking motifs belong to γ-motif, rich in π···π interactions and form infinite face-to-face stacks, β and δ forms featured with dimer unit and the π···π stacking motifs belong to γ- and herringbone-motif, respectively, the herringbone motif of δ form rich in C-H···π and edge-to-face interactions. We also correlated the phase transformation points of α, β, and δ PZA forms with the ratio of the percentage surface coverage of the N-H···O hydrogen bonds over that of the N-H···N hydrogen bonds, and found a negative correlation. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three methoxy- and methyl-substituted indole-3-acetonitriles (IAN) (4-OCH-IAN, 5-OCH-IAN and 7-CH-IAN) are reported in this work. Their structures were characterized by infrared spectra, elemental analyses, NMR spectra, differential scanning calorimetry, thermogravimetric analyses, and hot stage microscopy. The Hirshfeld surface analysis in terms of intermolecular interactions and π···π stacking motifs of the three substituted IANs was investigated in detail, and the results revealed that the different kinds of substituent groups as well as different substituted positions have a significant effect on the crystal structures, molecular π···π stacking motifs, melting points, and the types of intermolecular interactions. [ABSTRACT FROM AUTHOR]

We here reported a series of co-crystal structure of pyrazinamide (PZA) with m-hydroxybenzoic acid (MHBA), p-hydroxybenzoic acid (PHBA) and 3,4-dihydroxy benzolic acid (3,4-DHBA) and obtained three co-crystals (co-crystal 1- 3, respectively) under the same conditions. These crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, thermogravimetric analyses, differential scanning calorimetry, and Raman spectrum analysis. The images of single crystal diffraction revealed that 1 was a 1:1 (PZA:MHBA) co-crystal, 2 was a 1:1 (PZA:PHBA) co-crystal, and 3 was a 1:1 (PZA:3,4-DHBA). The strong O-H···O, N-H···O hydrogen bonding interactions between PZA and hydroxyl-substituted benzoic acid primarily made the structure of co-crystals stabilized. Hirshfeld surface and fingerprint plots of the three co-crystals showed that the structures were stabilized by H···H, O-H···O, N-H···O C-H···π, and π···π intermolecular interactions. [ABSTRACT FROM AUTHOR]

For the development of dispersible tablets of itraconazole (ITR), techniques of thermal, Raman spectroscopy, and isothermal stress testing (IST) were used to assess the compatibility of ITR with selected excipients. Initially, differential scanning calorimeter (DSC) was used to evaluate the compatibility. Raman spectrum of drug-excipient mixture was also compared with that of pure drug and excipient. Compatibility of excipients defined in the prototype formula was tested using IST. Based on the DSC results alone, PEG-4000 was found to exhibit interaction with ITR. However, the results of Raman and IST studies showed that all the excipients used in the formula were compatible with ITR. Overall, compatibility of excipients with ITR was successfully evaluated using the combination of DSC, Raman spectroscopy, and IST techniques. [ABSTRACT FROM AUTHOR]

Four rotator–stator assembly complexes: benzoic-4-methylammonium-tetrafluoroborate-15-crown-5 ([C8H10NO2-(15-crown-5)]+[BF4]−, 1); benzoic-4-methylammonium-perchlorate-15-crown-5 ([C8H10NO2-(15-crown-5)]+[ClO4]−, 2); benzoic-4-methylammonium-tetrafluoroborate-18-crown-6 ([C8H10NO2-(18-crown-6)]+[BF4]−, 3); benzoic-m-ammonium-tetrafluoroborate-18-crown-6 ([C7H8NO2-(18-crown-6)]+[BF4]−, 4), for the investigation of the supramolecular assembly and host–guest interaction of crown ethers, have been synthesized and characterized. The results revealed that the variation of crown ethers, the substituent position of carboxyl group, as well as the different kinds of inorganic anions all can lead to quite another geometry and directionality of both the anilinium rotors and crown ether stators, which lead to entirely different supramolecular architectures. It is interesting that the optimal distances from the mean O-plane where found for the 18-crown-6 macrocycle with the ammonium cation, and the conformation of the macrocycle was badly affected in complexes with shorter or longer distances. We also studied the Raman spectroscopy of the five complexes, which give further inspection of the intermolecular interactions. [ABSTRACT FROM AUTHOR]

The crystals of two organic salts of tris(hydroxymethyl)aminomethane (THAM) with p-hydroxybenzoic acid (PHBA) and salicylic acid (SA) were obtained. Their crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, differential scanning calorimetry, thermogravimetric analyses and hot stage microscopy. Wherein, 1 forms a 1:1 (THAM:PHBA) salt, and 2 forms a 2:2:1 (THAM:SA:HO) salt. The structure determination shows that the two salts are all primarily stabilized by strong O···H hydrogen bonds interaction between THAM and the two acids. The Hirshfeld surfaces and fingerprint plots of the reported salts were prepared and analyzed and reveal that the structures are stabilized by O···H, H···H, C···H, O···O and O···C intermolecular interactions. Graphical Abstract: The paper is about synthesis, crystal structure, thermal and Hirshfeld surfaces analysis of two THAM salts.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An investigation into the substituent effect of halogen atoms (F, Cl, Br) on the crystal structure of indole-3-carboxylic acid (ICA) was prepared in this work. The investigation was done through the aspect of crystal structure, intermolecular interactions and π…π stacking motifs with the assistance of infrared spectra, elemental analyses, NMR spectra, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and hot stage microscopy (HSM) measurements. The results revealed that the different kinds of halogen atoms and the different substituted positions have a significant effect on the crystal structures, molecular π…π stacking motifs and the kinds of intermolecular interactions. We further correlated the melting points of the ICAs with the H–H, O–H and X–H (X = F, Cl, Br) interactions, and found a positive correlation between them. [ABSTRACT FROM AUTHOR]

In-situ Attenuated total reflectance Fourier transform infrared (ATR-FTIR), focused beam reflectance measurement (FBRM) and particle video microscope (PVM) have been used simultaneously in this work to monitor the concentration, supersaturation, chord length distribution, and crystal habit, respectively, during a cooling crystallization process of Methyprednisolone Hemisuccinate (MPHS) from ethanol system. We developed a new calibration method based on peak ratios for the assessment of the concentration, solubility, and supersaturation in the 20–60°C temperature range. The crystallizations were conducted at two concentrations (7.5 and 9.5% w/w) with three different cooling rates (0.3, 0.5, and 0.7 K/min). The lower concentration was chosen within the constructed calibration range while the higher one was outside the calibration range and it was used to examine the extrapolating and predicting ability of the constructed calibration curves. The metastable zone widths (MSZW), supersaturation at nucleation, and the number of fine particle chord length of MPHS were all increased with the cooling rate, while the number of the larger chord length decreased with the increasing of the cooling rate. [ABSTRACT FROM AUTHOR]

The complex [Cu2(μ-L)2]. DMF (L = 2, 2'-[1-(2, 4, 6-trichlorophenyl)-1H-1, 2, 4-triazole-3, 5-diyl] diphenolate) has been prepared and its structure determined. The two CuII ions are four-coordinated in a planar structure, with the DMF molecule wrapped in the 'wings' of ligand L. Hirshfeld surface and fingerprint plots reveal that the complex structure is stabilised mainly by H···H, C-H ... Cl, C-H···π,π···π and lone-pair···π (C-Cl) intermolecular interactions. [ABSTRACT FROM AUTHOR]

The complex [N(CH3)4]3[Mn3Zn2(3,5-dibromosalox)3O(N3)6Cl2] has been synthesised and characterised. It crystallises as two independent molecules and exhibits a planar [MnIII3-(μ3-oxo)] core as well as μ2-η1:η1-azide bridging geometry. DNA binding studies show that the complex binds with DNA through intercalation. [ABSTRACT FROM AUTHOR]

Two new 1-D coordination polymers [ M (3-Bzpy)(N(CN))] ( M = Cd ( 1), Cu ( 2), 3-Bzpy = 3-benzoylpyridine) have been synthesized and structurally characterized by single-crystal X-ray diffraction and IR. Single-crystal X-ray diffraction reveals that the complexes 1 and 2 are isostructural and all crystallize in monoclinic P2/ c space group with cell dimensions: a = 6.3889(16) Å, b = 7.6496(12) Å, c = 26.767(6) Å, β = 99.131(19)°, V = 1291.6(5) Å, Z = 2 for 1 and a = 6.4483(9) Å, b = 7.5449(10) Å, c = 25.965(4) Å, β = 98.559(10)°, V = 1249.2(3) Å, Z = 2 for 2. Structure analysis manifest that 1 and 2 are all 1-D chains structures which parallel to the crystallographic b axis through end-to-end coordination by bidentate bridging dicyanamide ligands. Magnetic property of complex 2 was further investigated. Graphical Abstract: The paper is about synthesis, crystal structure and magnetic property of two new 1-D coordination polymers. Perspective view down the a-axis of complex 1 with thermal ellipsoids drawn at the 50% probability level [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Owing to the critical roles it plays for both structure and functionality, hydrogen bonding has high hopes for the orientated applications in hydrogen‐bonded organic frameworks (HOFs). Here in this work, a hydrogen‐bonding strategy is performed for adjusting the structure and functionality of a heme‐like ligand meso‐tetra(carboxy‐phenyl)‐porphyrin (TCPP) with co‐former 1,3‐di(4‐pyridyl) propane (1,3‐DPP). A 3D dynamic HOF TCPP‐1,3–DPP, with permanent porosity is obtained. For this HOF, the two components form novel robust 1D porous stripes, with the 1,3‐DPP molecules acting as the lining for the pores that are confined within the region between adjacent carboxyphenyl moieties of TCPP. This confinement has tuned the affinities of TCPP from hydrophobic into hydrophilic. Interestingly, the 1D stripes are further stacked by weak π...π interactions into a 3D framework, the latter is highly dynamic with 1D stripes sliding back and forth, upon pressurized and water adsorption in the solid‐state under ambient conditions, respectively. The activated TCPP‐1,3–DPP has a Brunauer–Emmett–Teller surface area of 258 m2 g−1, and shows a maximum adsorption capacity about 9.8% for water during the adsorption–desorption cycles, demonstrating a promising candidate for the real‐world application in effective dehydration of industrial gases under ambient conditions. A 3D dynamic hydrogen‐bonded organic framework TCPP‐1,3–DPP, which is composed of 1D porous stripes, shows permanent porosity and highly affinity to water. The activated species exhibit a maximum adsorption capacity about 9.8% for water during the adsorption–desorption cycles, demonstrating a promise for the real‐world application in effective dehydration of industrial gas under ambient condition. [ABSTRACT FROM AUTHOR]