A novel one-dimensional thiocyanate-bridged cobalt(III) complex: synthesis, crystal structure characterization and Hirshfeld surface analysis

A new one-dimensional thiocyanate-bridged cobalt(III) Schiff base complex, namely, catena-poly[[[4-bromo-2-((Z)-{[2-(thiophen-2-yl)ethyl]imino}methyl)phenolato-κ2N,O]cobalt(III)]-μ-thiocyanato-κ2N:S], [Co(SCN)(C13H11BrNOS)2]n or [Co(μ1,3-SCN)L2]n (1), where HL is 4-bromo-2-((Z)-{[2-(thiophene-2-yl)ethyl]imino}methyl)phenol, a bidentate Schiff base prepared from the condensation reaction of 5-bromosalicylaldehyde and 2-(thiophen-2-yl)ethylamine, has been synthesized by stirring Co(ClO4)2·6H2O, the Schiff base HL and ammonium thiocyanate (in a 1:2:1 molar ratio) in ethanol medium. The complex was characterized by FT-IR, electronic spectra and single-crystal X-ray diffraction (SC-XRD) studies. The SC-XRD data suggest that the compound crystallizes in the orthorhombic space group Pca21. The CoIII ion in 1 adopts a distorted octahedral geometry, the metal sites being six-coordinated by one thiocyanate N atom and one thiocyanate S atom in apical positions, and by two imine N atoms and two phenolate O atoms from two anionic L- ligands which form the basal plane. The thiocyanate ligand acts as a μ-1,3 bridge, joining neighbouring CoIII atoms and forming a uniform zigzag one-dimensional polymeric chain. The crystallographic data were also used in the Hirshfeld surface (HS) analysis, which aimed to investigate the nature and quantitative significance of any noncovalent intermolecular interactions inside the crystal lattice. The crystal void parameters have also been computed and show the molecules to be tightly packed.

Bisimidazole-based phosphorescent thiocyanatocadmates

Simple room-temperature self-assemblies between Cd2+ salts, SCN- and bisimidazole molecules at pH = 2 created three new organically templated thiocyanatocadmates [H2(L1)][Cd(SCN)4]·H2O (L1 = 1,4-bis(1H-imidazol-1-yl)benzene) 1, [H2(L2)][Cd(SCN)4] (L2 = 1,3-bis(2-methylimidazol-1-yl)propane) 2, and [H2(L3)][Cd2(SCN)6] (L3 = 1,4-bis(2-methyl-1H-imidazol-1-yl)butane) 3. X-ray single-crystal diffraction analysis reveals that (i) in 1-3, the SCN- groups doubly bridge the Cd2+ centers to form different thiocyanatocadmates: a linear chain in 1; a zigzag chain in 2; and a 2-D layer network (63 net) in 3; and (ii) in 1, via Nbase-HNSCN interactions, the L1 molecules extend the thiocyanatocadmate chains into a 2-D supramolecular layer, whereas in 2, the zigzag thiocyanatocadmate chains self-assemble into a 3-D supramolecular network via weak SS interactions. Photoluminescence analysis indicates that the three title compounds all emit light: blue light for 1 and 2 and green light for 3. At low temperatures, the emission positions of the three compounds hardly change, but the emission intensities are largely enhanced. Interestingly, after turning off the UV lamp, 1 and 2 still briefly emit light (ca. 2 s), which means that 1 and 2 possess phosphorescence properties. Phosphorescence lifetimes at 77 K are 1619 ms for 1 and 247 ms for 2.

New organically templated thiocyanatocadmates and chlorocuprate(II): synthesis and structural characterization

With various organic base molecules as the countercations, five new thiocyanatocadmates [H2(tmen)][Cd(SCN)4] (tmen = N,N,N',N'-tetramethylethylenediamine) 1, [H2(tmba)][Cd2(SCN)6] (tmba = N,N,N',N'-tetramethyl-1,4-butanediamine) 2, [H2(teen)][Cd2(SCN)6] (teen = N,N,N',N'-tetra-ethylethylenediamine) 3, [H(amp)][Cd(SCN)2(CH3COO)] (amp = 2-amino-6-methylpyridine) 4 and [H(abp)]4[Cd(SCN)4]SO4·H2O (abp = 2-amino-6-bromopyridine) 5, and one new chlorocuprate(II) [H2(cha)][CuCl4] (cha = 1,4-cyclohexanediamine) 6 were obtained from a series of simple room-temperature self-assemblies at pH = 2 or 6.5. X-ray single-crystal diffraction analysis reveals that (i) templated by [(CH3)2NH(CH2)2NH(CH3)2](2+) (H2(tmen)(2+)), the anion [Cd(SCN)4](2-) in 1 shows a 1-D linear single-chain structure, whereas templated by [(CH3)2NH(CH2)4NH(CH3)2](2+) (H2(tmba)(2+)), the anion [Cd2(SCN)6](2-) in 2 shows a 1-D linear double-chain structure. The number of C atoms between the two N atoms in the templating agent controls the width of the anionic chain through the N(amino)-H···N(SCN) interactions; (ii) templated by [(C2H5)2NH(CH2)2NH(C2H5)2](2+) (H2(teen)(2+)), the anion [Cd2(SCN)6](2-) in 3 exhibits a 3-D open-framework structure, which is based on zigzag anionic chains. A direct change of the substituent group from -CH3 to -C2H5 alters indirectly the shape of the anionic chain from a linear shape to a zigzag shape; (iii) 4 shows a 3-D supramolecular network structure, which is built up from the 1-D zigzag anionic structures by the H(amp)(+) molecules via N-H···O interactions. The formation of the zigzag chain derives from the chelation of the CH3COO(-) groups to the Cd(2+) centers; (iv) 5 is indeed a double salt of [H(abp)]2[Cd(SCN)4] and [H(abp)]2SO4. SO4(2-) and H(abp)(+) form a supramolecular aggregation. Surrounded by the aggregations, the anion [Cd(SCN)4](2-) only shows a dinuclear structure; and (v) templated by H2(cha)(2+), the anion [CuCl4](2-) in 6 displays a 2-D perovskite layer structure. The photoluminescence analysis indicates that upon excitation (λ(ex) = 335 nm for 4, λ(ex) = 395 nm for 5), and emit light (λ(em) = 365 nm for 4, λ(em) = 470 nm for 5), which can be seen clearly under the UV lamp.

4-(4-Carboxyphenoxy)phthalate-based coordination polymers and their application in sensing nitrobenzene

Structural characterization of 4-(4-carboxyphenoxy)phthalate-based Cd²⁺ and Mn²⁺ coordination polymers are reported, and Cd²⁺ coordination polymer can serve as probe to sense nitrobenzene.

New 1-D and 3-D thiocyanatocadmates modified by various amine molecules and Cl−/CH3COO− ions: synthesis, structural characterization, thermal behavior and photoluminescence properties

Reactions of CdCl₂/Cd(CH₃COO)₂, SCN⁻ and various organic amines yielded five new thiocyanatocadmates; structural, thermal and photoluminescence properties are reported.