Crystal structures, electron spin resonance, and thermogravimetric analysis of three mixed-valence copper cyanide polymers

The crystal structures of three mixed-valence copper cyanide alkanolamine polymers are presented, together with thermogravimetric analysis (TGA) and electron spin resonance (ESR) data. In all three structures, a CuII moiety on a crystallographic center of symmetry is coordinated by two alkanolamines and links two CuICN chains via cyanide bridging groups to form diperiodic sheets. The sheets are linked together by cuprophilic CuI-CuI interactions to form a three-dimensional network. In poly[bis(μ-3-aminopropanolato)tetra-μ-cyanido-dicopper(I)dicopper(II)], [Cu4(CN)4(C3H8NO)2]n, 1, propanolamine bases have lost their hydroxyl H atoms and coordinate as chelates to two CuII atoms to form a dimeric CuII moiety bridged by the O atoms of the bases with CuII atoms in square-planar coordination. The ESR spectrum is very broad, indicating exchange between the two CuII centers. In poly[bis(2-aminopropanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu3(CN)4(C3H9NO)2]n, 2, and poly[bis(2-aminoethanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu3(CN)4(CH7NO)2]n, 3, a single CuII atom links the CuICN chains together via CN bridges. The chelating alkanolamines are not ionized, and the OH groups form rather long bonds in the axial positions of the octahedrally coordinated CuII atoms. The coordination geometries of CuII in 2 and 3 are almost identical, except that the Cu-O distances are longer in 2 than in 3, which may explain their somewhat different ESR spectra. Thermal decomposition in 2 and 3, but not in 1, begins with the loss of HCN(g), and this can be correlated with the presence of OH protons on the ligands in 2 and 3, which are not present in 1.

Series of Cadmium-Organic Frameworks Based on Mixed Flexible and Rigid Ligands: Single-Crystal-to-Single-Crystal Transformations, Sorption, and Luminescence Properties

Here, we present a series of Cd(II) coordination polymers containing two types of ligands: sterically rigid terephthalate derivatives (bdc-NO22- and bdc-Br2-) and flexible bis(2-methylimidazolyl)propane (bmip). The combination of two types of ligands is used to obtain and characterize compounds by single crystal and powder X-ray diffraction, FT-IR, elemental analysis, and TGA. Guest exchange results in structural transformations. 2-fold interpenetrated 1·DMF and 2·DMF rapidly undergo to 4-fold interpenetrated 1·Et2O, 1·EtOH, and 1·H2O, or 2·Et2O, respectively. Also, changes in the coordinating numbers and length of the N,N'-donor bmip ligand were observed according to single crystal X-ray analysis. Activated guest-free compounds [Cd(bdc-NO2)(bmip)] (1) and [Cd(bdc-Br)(bmip)] (2) are shown to be porous with a BET surface area of 103 and 283 m2·g-1, respectively. Moreover, both compounds demonstrate gate-opening behavior of ethylene adsorption isotherms at low pressures (<1 bar) and highly selective adsorption of benzene over cyclohexane or lower alcohols. Also, both compounds demonstrate a strong dependence of the maximum of the photoluminescence emission on an excitation wavelength. As a result, the photoluminescence color changes from white to red and from blue to red through green and yellow for compounds 1 and 2, respectively, with excitation wavelength changing from 360 to 540 nm.

Ratiometric luminescent sensing of a biomarker for sugar consumption in an aqueous medium using a Cu(II) coordination polymer

An innovative [Cu(Hadp)₂(Bimb)]_n (KA@CP-S3) coordination polymer expands its dimensionality from a 1D chain to a 2D network. The topological analysis reveals that KA@CP-S3 has 2-connected uninodal 2D 2C1 topology. KA@CP-S3 has capable luminescent sensing for volatile organic compounds (VOCs), nitroaromatics, heavy metal ions, anions, disposed antibiotics (nitrofurantoin and tetracycline) and biomarkers. Intriguingly, KA@CP-S3 exhibits outstanding selective quenching of about 90.7% and 90.5% for the 125 mg dl^-1 and 150 mg dl^-1 strengths of sucrose, respectively, in aqueous solution along with other ranges in between. The photocatalytic degradation efficiency of KA@CP-S3 for the potentially harmful organic dye Bromophenol Blue displays 95.4%, which is the highest among the 13 dyes that were evaluated.

Synthesis of a Mixed-Ligand H-Bonded Cu Coordination Polymer: Exploring the pH-Dependent High Photocatalytic Degradation of Rhodamine 6G, Methyl Violet, Crystal Violet, and Rose Bengal Dyes under Room Illumination

A new mixed-ligand H-bonded coordination polymer {[Cu2(Or)2(Bimb)3]·4H2O} n (KA@CP-S) has been prepared hydrothermally using basic copper carbonate with 1,4-bis[(1H-imidazol-1-yl)methyl]benzene (Bimb) and potassium orotate (OrK) ligands. According to topological studies, KA@CP-S has a new topology with a three-connected uninodal net with point symbol (PS) {82·12}2{8}3. The KA@CP-S was employed as a catalyst for screening of a series of harmful cationic, anionic, and neutral organic dyes in contaminated water. The photocatalytic degradation study shows that it exhibits good catalytic efficiency for cationic dyes like Crystal Violet (CV, 75.8%), Methyl Violet (MV, 76.8%), and Rhodamine 6G (Rh6G, 86.5%) and Rose Bengal (RB, 76.1%), which is an anionic dye, while for a neutral dye, its catalytic efficiency is only 72% (Neutral Red) at ambient temperature. The effect of pH on photocatalytic degradation was also analyzed. The degradation experiment reveals that the detection limits of KA@CP-S for mostly catalyzed colorant concentrations in contaminated water are 0.60 ppm (CV), 0.20 ppm (RB), 0.33 ppm (MV), and 0.20 ppm (Rh6G) at pH 12, 4, and 10. The degradation of dyes follows pseudo-first-order kinetics. The excellent catalytic property and regeneration ability of KA@CP-S make it a potential and efficient future remedial material for the detection and separation of toxic dyes from wastewater contaminated by industrial effluents.

Polytorsional-amide/carboxylates-directed Cd(ii) coordination polymers exhibiting multi-functional sensing behaviors

By rational assembly of polytorsional-amide [N,N′-bis(4-methylenepyridin-4-yl)-1,4-naphthalene dicarboxamide (L)] and polytorsional-carboxylates [H₂ADI = adipic acid, H₂PIM = pimelic acid, H₂SUB = suberic acid], three new Cd-based coordination polymers (CPs) C₃₀H₃₀CdN₄O₇ (1), C₃₁H₃₂CdN₄O₇ (2) and C_31.03H_30.55CdCl_0.24N₄O_5.52 (3) were successfully synthesized. CPs 1–2 and 3 are 2D networks and a 3D framework, which all display 3,5-connected topologies with different structural details. The effects of carboxylates with different carbon chains on the structure of the complexes were studied. Fluorescence experiments show that CPs 1–3 have good multi-functional sensing ability for metal cations (Fe³⁺), anions (MnO₄⁻, CrO₄²⁻, Cr₂O₇²⁻) and organochlorine pesticides (2,6-dichloro-4-nitroamine) with good anti-interference and recyclable characteristics. The possible sensing mechanism is also investigated in detail.

Three (3,5)-connected Cd(ii) coordination polymers induced by polytorsional-amide/carboxylates exhibiting controllable multifunctional fluorescent sensing activities.

Auxiliary ligand-modulated trisimidazole-based coordination polymers: syntheses, structures and photoluminescence properties

Five coordination polymers having 1,3,5-tris(1-imidazolyl)benzene and the varied O-donor auxiliary ligands were designed and synthesized. Further, the auxiliary ligands modulated these complexes with structural diversities and novel topologies.

Cu(i) Iodide coordination polymers with aromatic thioamides

The reaction of 4-pyridinethiobenzamide (PyTBA) with CuI and KI aqueous solution in acetone or THF under slow diffusion gives rise to the formation of single crystals of two coordination polymers [CuIPyTBA]_n·nS (S = acetone; 1/3THF).