•A new structure of BM-5-CATP was isolated using methanol as crystallization solvent.•The two structures derived from different solvents were compared and analyzed in detail.•A new Co(II) complex was prepared and it displayed reversible photo-isomerization in solid state.Crystallization from methanol of 1,2-bis(2′-methyl-5′-(carboxylic acid)-3′-thienyl)perfluorocyclopentene (BM-5-CATP, H2L) afforded a new single crystal (H2LMeOH) characterized by single crystal X-ray diffraction analysis, whose structure is different from those of the known crystals crystallized from ethanol, acetone/hexane or acetonitrile. There are two independent molecules with different conformations in one asymmetric unit of H2L. One is a photo-active anti-parallel conformation in which the reactive C atoms are separated by 3.90 Å whereas the other is a photo-inactive parallel conformation in which the reactive C-C distance is 4.42 Å. The packing characteristics of the two structures derived from methanol and ethanol were compared and analyzed in detail helped by the corresponding computational analyses. The photo-isomerizations of H2LMeOH in tetrahydrofuran and in solid state occur reversibly upon alternate irradiation with ultraviolet (λ = 254 nm) and visible light (λ > 550 nm).Reaction of CoCl2·6H2O with BM-5-CATP in methanol afforded a new complex [CoL(MeOH)4](MeOH) (1). Complex 1 is revealed by X-ray crystal diffraction as a 1D zigzag chain, where BM-5-CATP serves as bis-monodentate ligand bridging Co(II) centers in syn-anti fashion. The two thienyl rings in 1 adopt anti-parallel fashions and the distances of 3.80 Å between two reactive carbons is short enough for the occurrence of photocyclizations. As expect, complex 1 displayed effective photo-isomerization in crystalline phase with color interconversion between pink and purple, indicating weak suppression of photochromism from metal coordination and extensive H bonds as well as Van de Waals contacts. The λmax of 1 (580 nm) in closed form shifted to longer wavelength compared with that of free ligand (576 nm).Crystallization from methanol of a dithienylethene (BM-5-CATP, H2L) afforded a new single crystal (H2LMeOH), where two independent conformations, i.e. photo-inactive parallel conformation and photo-reactive anti-parallel conformation, coexisted. Coordination of Co(II) with H2L in methanol gave rise to complex 1, which displayed typical photochromic reactions in crystalline phase. The complexation of metal ions did not suppress the photochromism of ligand in crystalline state.Download high-res image (99KB)Download full-size image

A new coordination compound was isolated by reaction of AgBF4 with cis-1,2-dicyano-1,2-bis(2′,4′,5′-trimethyl-3′-thienyl) ethene (cis-dbe) in benzene with the aim of suppressing cis-trans photo-isomerization of cis-dbe by the steric hindrance from metal coordination. The complex was revealed as a dinuclear structure by single crystal X-ray diffraction, where two Ag(I) ions are bridged by two cis-dbe molecules via their four N atoms of cyano groups. The benzene, employed as crystallized solvent in synthesis, was revealed to coordinate with metal center. The ligand presents as cis configuration and the two thiophene rings adopt anti-parallel conformation with reactive C distance of 3.46 Å, which is short enough for the photo-cyclization. These structural features are favorable for the ring-closure reaction. On the other hand, BF4− is existed as counter anion sandwiched between the neighboring dinuclear complexes via extensive intramolecular hydrogen bonds and Van de Waals contacts. Also, strong π-π interactions exist in the complex. These weak interactions are theoretically disadvantageous to the photo-cyclization.As expected, the cis-trans photo-isomerization was successfully suppressed by involving of cis-dbe into coordination bonds and rational selecting of 405 nm excitation light as evidenced by UV–Vis spectra and 1H NMR studies. And the reversible ring-closing and ring-opening reactions with color inter-conversion between yellow and red were not prohibited in solution, solid state and PMMA films, suggesting an indistinctive effect of metal coordination on ring closure.Integrate of AgBF4 with photochromic cis-dbe resulted a new complex, which shows a dinuclear structure and complicated intermolecular H bonds as well as π-π interactions. The strategy successfully suppressed the cis-trans isomerizations not only in complex crystallization but also the photo-excitation process. The reversible photochemical ring-closure and ring-opening were however not be prohibited.Download high-res image (80KB)Download full-size image

•Three unique Ag(I) coordination polymers with p-phenylenediacetonitrile were isolated by solvent-regulating strategy.•Solvent can influence the crystal structure by acting as guest and without involving in coordination.•The solvent-free form of 1 occurred a phase transition by re-crystallization of 1 from DMSO.Three unique complexes with diverse coordination architectures were synthesized upon complexation of p-phenylenediacetonitrile with silver trifluoroacetate in response to regulation of solvents system. Crystallization from benzene and m-xylene yield two 2D layered frameworks 1 and 2, respectively, of which 1 contains benzene as guest but 2 does not. In 1, every two ligands double link two 1D chains in trans fashion while each ligand is μ2-bridged to two 1D chains in 2. This difference in coordination can be properly assigned to the significant solvent steric effect on assembled reactions, which ultimately leads to two types of pores with different size and shape formed within the 2D structure of 1 and 2, respectively. 3 was recrystallized of guest-eliminated 1a from DMSO and share the same chemical formula with 1a, yet differ greatly in coordination topology, demonstrating the solvent-mediated crystallization and phase transition.The benzenes in 1 could be liberated accompanying the observable distortion of its framework as evidenced by XRPD. The guest-eliminated 1a declined the reincorporation of aromatic guests such as benzene, toluene and xylene isomers due to the probable shrinkage of pores in 1a, but accommodated those smaller guests such as water, methanol and ethanol.Three unique Ag(I) complexes based on p-phenylenediacetonitrile were synthesized by regulation of solvents system. Crystallization from benzene and m-xylene yielded two distinct 2D layered frameworks 1 and 2, respectively. Recrystallization of guest-eliminated 1a from DMSO produced 3 with different structure from 1a yet same chemical formula.

A homochiral three-dimensional framework material, [Cu7(4-bpt)6(CN)(H2O)] (1) (4-bpt = 3,5-bis(4-pyridyl)-1,2,4-triazole), has been successfully synthesized by solvothermal reaction, which is generated through an unusual spontaneous asymmetrical crystallization from achiral precursors, and its photocatalytic properties in degradation of organic dyes are also investigated.

•Two Ag(I) coordination polymers with 1,4-dicyanobenzene were prepared.•Coordinated trifluoroacetate and triflate anions play different roles in the construction of final frameworks.•The guest molecules in complex 1 could be completely liberated, reincorporated and replaced.•Complex 1 shows a preferential adsorption of m-xylene over other xylene isomers.Complexes {[Ag5(CF3COO)5(1,4-dcb)2].2(C6H6)}n (1) and [Ag2(CF3SO3)2(1,4-dcb)2(μ-H2O)]n (2) were synthesized by reaction of 1,4-dicyanobenzene (1,4-dcb) with AgX (X = CF3COO− or CF3SO3−). Both of them have been characterized by FT-IR, elemental analysis and single-crystal X-ray diffraction. Complex 1 forms 2-D sheets which are constructed from cross-linked 1,4-dcb and 1-D silver(I) chains connecting through trifluoroacetate anions. Benzenes are intercalated as guests between the sheets of complex 1. Complex 2 forms double-strand chains which are built on bimetal centers bridged by a μ-H2O and double bridging 1,4-dcb ligands coordinating via terminal N-donors.Interestingly, the framework of 1 reversibly responds to the removal and inclusion of benzenes. In addition, benzene-eliminated 1 could adsorb toluene and shows a preferential adsorption of m-xylene over other xylene isomers.By employing trifluoroacetate and triflate as anions, two architecturally distinct Ag(I) coordination polymers with 1,4-dicyanobenzene were synthesized and crystallographically characterized. Complex 1 forms 2-D sheets with benzenes intercalated between layers. Complex 2, on the other hand, forms double-strand chains. Interestingly, the guest benzenes in 1 could be completely liberated and reincorporated with the framework reversibly responding to the removal and inclusion of benzenes. Furthermore, complex 1 could absorb m-xylene while blocking its ortho and para isomers.

A novel Ni(II) coordination polymer with flexible 4,4′-oxybis(benzoic acid) (oba) and rigid 4,4′-bipyridine was prepared hydrothermally and crystallographically characterized. It shows an unusual μ-oxo(O2−) bridged dinickel(II) polymer. In the dimetal core, each metal center is six-coordinated to three carboxylate oxygen atoms from two different oba ligands, two nitrogen atoms of distinct 4,4′-bipyridine and one bridging oxygen forming a distorted octahedron.Upon complexation, nickel complex exhibits intense purple fluorescence (413.8 nm) which may originates to the O2−Ni2+(LMCT) in addition to the peaks of intraligand π–π∗ transition of oba ligand (317.7 and 720.7 nm). Moreover, nickel crystals possess preferable photocatalytic decomposition of RhB solution.Graphical abstractA novel Ni(II) coordination polymer with flexible 4,4′-oxybis(benzoic acid) and 4,4′-bipyridine was prepared hydrothermally and crystallographically characterized. It shows an unusual μ-oxo(O2−) bridged dinickel(II) polymer where each metal center is six-coordinated to three carboxylate oxygen atoms, two nitrogen atoms and one bridging oxygen forming a distorted octahedron. Incorporation of Ni ions and 4,4′-oxybis(benzoic acid) into polymer generate intense purple fluorescence and possess preferable photocatalytic decomposition of RhB solution.Highlights► Novel Ni(II) coordination polymer with 4,4′-oxybis(benzoic acid) and 4,4′-bipyridine was prepared. ► It shows an unusual μ-oxo(O2−) bridged dinickel(II) center. ► Nickel complex exhibits intense purple fluorescence (413.8 nm) which may originates to the O2−Ni2+(LMCT). ► Nickel crystals possess preferable photocatalytic decomposition of RhB solution.

A homochiral three-dimensional framework material, [Cu7(4-bpt)6(CN)(H2O)] (1) (4-bpt = 3,5-bis(4-pyridyl)-1,2,4-triazole), has been successfully synthesized by solvothermal reaction, which is generated through an unusual spontaneous asymmetrical crystallization from achiral precursors, and its photocatalytic properties in degradation of organic dyes are also investigated.