3D Supramolecular Network Research Articles

Synthesis, structure, theoretical calculation and antibacterial property of two novel Zn(II)/Ni(II) compounds based on 3, 5-dichlorosalicylaldehyde thiocarbamide ligand

Two new compounds namely [Zn(L1)phen]31 and Ni(L1)phen(MeOH) 2 (L1 = 3, 5-dichlorosalicylaldehyde thiosemicarbazone) were synthesized by the slow evaporation method at room temperature. The structure of ligand L1 was determined using 1H NMR and 13C NMR spectra. X-ray single crystal diffraction analysis revealed that compounds 1–2 can form 3D supramolecular network structures through π···π stacking and hydrogen bonding interactions. The DFT calculation shows that the coordination of ligand and metal is in good agreement with the experimental results. Hirshfeld surface analysis revealed that H…H and Cl…H interactions were the predominant interactions in compounds 1–2. Energy framework analysis indicated that dispersion energy played a dominant role in the energy composition of compounds 1–2. The inhibitory effects of compounds 1–2 against Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA) were tested using the paper disk diffusion method (1: E. coli: 18 mm, MRSA: 17 mm, 2: E. coli: 15 mm, MRSA: 16 mm). Ion releasing experiments were conducted to assess the ion release capacity of compounds 1–2 (Zn2+, 4 days, 38.33 µg/mL; Ni2+, 4 days, 29.12 µg/mL). Molecular docking demonstrated the interaction modes of compounds 1–2 with UDP-N-acetylenolpyruvoylglucosamine reductase (MurB) and dihydrofolate reductase (DHFR) in bacteria, involving hydrophobic, stacking, hydrogen bonding and halogen bonding interactions. The generation of reactive oxygen species (ROS) in bacteria under the presence of compounds 1–2 were evaluated using a fluorescent dye known as dichlorodihydrofluorescein diacetate (DCFH-DA). Potential antibacterial mechanisms of compounds 1–2 were proposed.

Synthesis, Structural Characterization and Hirshfeld Surface Analysis of a Novel Cd(II) Coordination Polymer with Mixed N- and O-donor Linker

In the present study, we report the room temperature synthesis of a novel two-dimensional (2D) coordination polymer (CP) having the formula {[Cd(H-PCA)2(H2O)].0.5(H2O).0.5(CH3OH)}n (CP1), where H-PCA represents 4-pyrazolecarboxylate. The synthesis of CP1 was achieved through a one-pot reaction, involving the self-assembly of Cd(OAc)2·2H2O and the multitopic mixed N- and O-donor ligand, 4-pyrazolecarboxylic acid (H2-PCA), in methanol. This method demonstrated high yield and purity, enabling the facile production of multigram quantities of CP1 within a short timeframe. Notably, the synthetic procedure selectively deprotonates the carboxylic acid group while retaining the pyrazole moiety in its protonated form.CP1 has been thoroughly characterized using various analytical techniques, including single-crystal X-ray diffraction, FTIR spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction. The structural analysis revealed that CP1 features a 3, 5-connected binodal net with the point symbol {4.5.6}{4.55.63.7}, leading to a unique –ths net topology. Through hydrogen bonding connections between adjacent 2D sheets, CP1 further extends into a three-dimensional (3D) supramolecular network due to the presence of coordinated water molecules and the protonated pyrazole group. Additionally, a 3D Hirshfeld Surface analysis accompanied by quantitative 2D fingerprint plots was also investigated to explore the intermolecular interactions.

New organic-inorganic hybrid ionic material Tris(melaminium) monodrogenphosphate dihydrogenphosphate tetrahydrate: Synthesis, single-crystal structure, Hirshfeld surface analysis, spectroscopic characterization, and thermal behavior

A novel type-I hybrid ionic material named Tris (melaminium) monodrogenphosphate dihydrogenphosphate tetrahydrate (3C3H7N6+.HPO42−.H2PO4−.4H2O) was synthesized. Its structure was affined by single crystal X-ray diffraction, illustrating that the material crystallizes in P1−triclinic system with cell parameters a = 11.2424(9)Å, b = 11.8460(9)Å, c = 11.983(9)Å, β=71.555(3)° and a filling rate Z = 2. The 3D-supramolecular network is constituted by non-stacked planar melaminium chains, laid along a diagonal direction of the unit cell, and joined indirectly via the inorganic part's molecules, forming lamellar material along Oc-direction; the various contacts were discussed through 3D-Hirshfeld surface analysis. The UV–visible spectroscopy reveals that this hybrid material is transparent in the visible and UV near visible domains, and has considerable absorption in middle and far UV. The several vibration modes were analyzed by FT-IR spectroscopy and correlated to the functional groups of the affined structure. The thermal decomposition behavior was studied by TGA/DTG and DSC techniques exhibiting a good thermal stability of 340 °C.

Synthesis, structure, photoluminescence and magnetism of a series of cobalt‐lanthanide heterometallic complexes originated from 2,3‐dichlorobenzoate and 1,10‐phenanthroline

AbstractA series of 3d–4f heterometallic complexes, namely [Ln2Co2(2,3‐DCB)10(phen)2] [Ln=Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Er (7)], were obtained through the self‐assembly reactions of Ln(NO3)3 ⋅ nH2O, Co(NO3)2 ⋅ 6H2O, 2,3‐dichlorobenzoic acid (2,3‐HDCB), NaOH and 1,10‐phenanthroline (phen) under solvothermal conditions. Their crystal structures were determined by single‐crystal X‐ray diffraction. They were also characterized by elemental analysis, FT‐IR, powder X‐ray diffraction (PXRD) and thermogravimetric analysis (TGA) and differential thermoanalysis (DTA). These seven complexes have the same molecular formula but different crystal structures. Complexes 1–3, 4 and 5 as well as 6 and 7 are crystallographically isomorphous, respectively. They all exhibit zero‐dimensional (0D) linear tetranuclear cluster structures. These 0D linear tetranuclear clusters can be further connected into a two‐dimensional (2D) supramolecular network via the extensive intermolecular π–π interactions between 2,3‐DCB and phen. The photoluminescent properties of 3, 5 and 6 and the magnetic properties of 1–2 and 4–7 were investigated. Complex 6 shows a slow magnetic relaxation behavior.

Toward conformational identification of molecules in 2D and 3D self-assemblies on surfaces

The design of supramolecular networks based on organic molecules deposited on surfaces, is highly attractive for various applications. One of the remaining challenges is the expansion of monolayers to well-ordered multilayers in order to enhance the functionality and complexity of self-assemblies. In this study, we present an assessment of molecular conformation from 2D to 3D supramolecular networks adsorbed onto a HOPG surface under ambient conditions utilizing a combination of scanning probe microscopies and atomic force microscopy- infrared (AFM-IR). We have observed that the infrared (IR) spectra of the designed molecules vary from layer to layer due to the modifications in the dihedral angle between the C=O group and the neighboring phenyl ring, especially in the case of a 3D supramolecular network consisting of multiple layers of molecules.

Two robust zinc(II) coordination polymers as dual functional sensors for selective and sensitive detection of sulfamethoxazole antibiotic and ferric ion

Two new zinc(II) coordination polymers (CPs), namely, {[Zn(BPDC)(L1)2·(H2O)2]·H2O}n (1) and {[Zn(BPDC)(L2)0.5·(H2O)]}n (2) (H2BPDC = Biphenyl-4,4′-dicarboxylic acid, L1 = 2-(2-(pyridin-3-yl)vinyl)-1H-benzimidazole, L2 = 1,1′-(1,6-hexanediyl)bis[2-(2-pyridyl)benzimidazole]) are hydrothermally synthesized and characterized. 1 possesses a straight chain, which is further extended into a 3D supramolecular framework through O−H···O and N−H···O hydrogen bonding interactions. 2 exhibits the hcb layer and further extended through O−H···O hydrogen bonding interactions into 3D supramolecular networks. The two CPs present thermal and pH stabilities. 1 and 2 can act as bifunctional fluorescent sensors for the selective detection of sulfamethoxazole and Fe3+ ion.

New Transition Metal Coordination Polymers Derived from 2-(3,5-Dicarboxyphenyl)-6-carboxybenzimidazole as Photocatalysts for Dye and Antibiotic Decomposition.

Coordination polymers (CPs) are an assorted class of coordination complexes that are gaining attention for the safe and sustainable removal of organic dyes from wastewater discharge by either adsorption or photocatalytic degradation. Herein, three different coordination polymers with compositions [Ni(HL)(H2O)2·1.9H2O] (1), [Mn3(HL)(L)(μ3-OH)(H2O)(phen)2·2H2O] (2), and [Cd(HL)4(H2O)]·H2O (3) (H3L = 2-(3,5-dicarboxyphenyl)-6-carboxybenzimidazole; phen = 1,10-phenanthroline) have been synthesized and characterized spectroscopically and by single crystal X-ray diffraction. Single crystal X-ray diffraction results indicated that 1 forms a 2D layer-like framework, while 2 exhibits a 3-connected net with the Schläfli symbol of (44.6), and 3 displays a 3D supramolecular network in which two adjacent 2D layers are held by π···π interactions. All three compounds have been used as photocatalysts to catalyze the photodegradation of antibiotic dinitrozole (DTZ) and rhodamine B (RhB). The photocatalytic results suggested that the Mn-based CP 2 exhibited better photodecomposition of DTZ (91.1%) and RhB (95.0%) than the other two CPs in the time span of 45 min. The observed photocatalytic mechanisms have been addressed using Hirshfeld surface analyses.

Two new Zn(II) and Cd(II) coordination polymers derived from 1,3,5-tris(3-carbonylphenyloxy)benzene and 4,4′-bis(imidazolyl)biphenyl ligands: Syntheses, structure and luminescent sensing of antibiotics

Two new coordination polymers with formulae [Zn(HL)(bb)]n (1) and [Cd(HL)(bb)]n (2) (H3L = 1,3,5-tris(3-carbonylphenyloxy)benzene and bb = 4,4′-bis(imidazolyl)biphenyl) have been synthesized solvothermally and structurally characterized by elemental analysis, IR, single crystal X-ray diffraction and thermal analyses. Single crystal X-ray diffraction studies reveal that compounds 1 and 2 show similar three-fold interpenetrating 4-connected 2D framework structure with the sql topological net and the Schläfli symbol of {44·62} and are further extended into 3D supramolecular network by inter-molecular hydrogen bonding. Compound 1 have been used as turn-off luminescent sensor and displayed sensitive and selective luminescence sensing for nitrofurazone antibiotic (NFZ) with Ksv of 0.87 × 103 M−1 and 1.98 ppm limit of detection (LOD). The plausible mechanistic pathway for the detrioration in the luminescent intensity of 1 in presence of antibiotics have been explained with the help of theoretical calculations. The calculations indicated that the decline in fluorescence intensity of 1 was accredited to the electron/energy transfer as well as weak interactions operating between 1 and antibiotic.

Enhancing photocatalytic degradation efficiency via the construction of organic/inorganic S-scheme supramolecular hybrid heterostructures

This study demonstrates the successful construction of a hybrid van der Waals heterostructure (vdWH) consisting of 3D supramolecular networks and 2D semiconductor Ag3PO4, using hydrogen-bonded 3D networks H12SubPcB-OPh2OH self-assembled onto Ag3PO4. The resulting organic/inorganic vdWH exhibits significantly enhanced photocatalytic degradation efficiency for oxytetracycline (OTC) and tetracycline (TC) under visible light irradiation, with apparent rate constants 1.8 and 1.5 times higher than those of pristine Ag3PO4, respectively. Moreover, after five photocatalytic cycles, the photocatalytic activity of vdWH was still much higher than that of pristine Ag3PO4. Molecular dynamics simulations indicate that the SubPc-3 supramolecular assembly is more prone to forming a 3D hydrogen bonding network rather than a 1D columnar stacking. In-situ irradiated X-ray photoelectron spectroscopy analyses and theoretical calculations confirm that the charge transfers between H12SubPcB-OPh2OH and Ag3PO4 are consistent with the S-scheme mechanism. This work provides a promising strategy for designing and fabricating efficient and stable supramolecular self-assembled semiconductor-based photocatalysts.

Synthesis, crystal structure study, thermal, Hirshfeld surface, optical and photoluminescence properties of new organic-inorganic hybrid material: (C6H5CH2N(C2H5)3)[Cd3Cl7

This work describes a new two-dimensional chlorocadmate (II) compound formulated us (C6H5CH2N(C2H5)3)[Cd3Cl7] has been synthesized by slow evaporation method at room temperature and characterized by single-crystal X-ray diffraction. Structural analysis reveals that this compound crystallizes in the triclinic system with centrosymetric P−1 space group. The molecular arrangement of the crystal displays a two-dimensional (2D) structure which consist in one (C6H5CH2N(C2H5)3)+cation and one anionic layers [Cd3Cl7]‒. The various components are interconnected through non-classical C–H…Cl hydrogen bonds, Coulombic attractions, and van der Waals interactions, which collectively secure the unity and stability of the crystal arrangement. This interaction ensemble contributes to the formation of a three-dimensional (3D) supramolecular network. The examination of the crystal structure provides a new interesting example of covalent polymeric layers of [Cd3Cl7]n. The intermolecular interactions were identified using Hirshfeld surfaces as well 2D-fingerprint plots. Furthermore, Infrared (IR) spectrum was analyzed, confirming the presence of the organic cation. Thermogravimetric analysis (TGA) reveals that the studied compound remains stable up to 266 °C. DSC thermogram shows that it undergoes two endothermic anomalies around 79.6 °C and 139 °C. Diffuse reflectance spectra (DRS) method was used to study the optical properties and shows that there is a strong absorption in the UV region for Cd hybrid. Kubelka–Munk equation has been used to calculate the band gap energy indicating that the material is a direct type (4.25 eV). Photoluminescence spectroscopy (PL) proves that the title material was well structured.

Combined Experimental and Computational Study of V-Substituted Lindqvist Polyoxotungstate: Screening by Docking for Potential Antidiabetic Activity.

In the current work, a novel vanadotungstate compound, (C6H9N2)4[V2W4O19]·2H2O (1), is isolated by a simple stepwise synthesis method and characterized by a combined experimental and computational study. Molecular docking is conducted for the first time for this kind of substituted Lindqvist polyoxometalates to elucidate for potential antidiabetic activity. Hence, the modeling results revealed a significant docking score of the reported compound to bind to the active sites of α-glucosidase with the lowest binding energy of -5.7 kcal/mol, where the standard drug acarbose (ACB) had -4.6 kcal/mol binding energy. The stability of binding was enhanced by strong H-bonding, van der Waals, and electrostatic interactions occurring in the three-dimensional (3D) supramolecular network of polyanionic vanadotungstate subunits templated with organic moieties as shown by X-ray diffraction and Hirshfeld analyses. Furthermore, density functional theory (DFT) calculations supported with photophysical measurements are also discussed to predict the most chemical and biological reactivity. In this view, the complete description of electronic and biological features of (1) is enhanced by determination of the highest occupied molecular orbital (HOMO)/least unoccupied molecular orbital (LUMO) energy, electronic density, ionization potential, electron affinity, etc. These chemical descriptors, intermolecular interactions, docking score, and binding free energy estimation are essential in understanding the reactivity of this bioactive compound offering potential inhibition of the α-glucosidase enzyme.

Synthesis of hydrogen bonded copper(II) coordination polymer: Photocatalytic degradation of Rose Bengal dye and luminescent sensing of Hg+2, Cr2O72−, and nitrofurantoin

A new helical coordination polymer, [Cu(Or)(H2O)3]n (KA@CP-ARS) has been synthesized at room temperature and examined using single-crystal X-ray diffraction (SC-XRD) and other analytical techniques. KA@CP-ARS formed 1D helical type structure via coordination bonding as well as a 3D supramolecular network through hydrogen bonding interactions. KA@CP-ARS manifested as a remarkable luminescent sensor for volatile organic compounds (VOCs), 3-Nitrophenol, Cr2O72−, Hg2+, creatinine, nitrofurantoin and sucrose (200 mg/dl) in particular along with the remarkable photocatalytic degradation of Rose Bengal (RB) dye with 96.54% efficiency. Overall this study demonstrates that the synthesized Cu-orotate coordination polymer has good luminescent sensing and catalytic degradation activity, therefore could be employed for a range of applications such as sensing of biomolecules like sucrose and photocatalysis of toxic dyes.

Four Cd(II)-CPs as dual-responsive luminescent probes for the sensing of Co2+/Hg2+ and chlortetracycline

Four new ternary Cd(II) coordination polymers (CPs) based on rarely-used 2-(pyridin-2-yl)-1-(pyridin-3-ylmethyl)-1H-benzo[d]imidazole (L) were synthesized via hydrothermal method, namely {[Cd(L)(H2DOBDC)]·H2O}n (1), {[Cd(L)(TP)]·2H2O}n (2), [Cd2(L)(DCTP)2(H2O)]n (3) and {[Cd2(L)(NDA)2]·H2O}n (4) (H4DOBDC = 2,5-dihydroxy terephthalic acids, H2TP = terephthalic acid, H2DCTP = 2,5-dichloroterephthalic acid and H2NDA = 1, 4-naphthalenedicarboxylic acid). 1 and 2 are 4-connected 2D sql layers, in which 2 is further expanded into a 3D supramolecular network by π − π stacking interaction, while 3 and 4 exhibit three-dimensional frameworks with unusual topology. 1 and 3/2 and 4 can act as dual-functional fluorescent sensors for the sensing of Hg2+/Co2+and chlortetracycline (CTC) with response times of 30 s for Hg2+/Co2+ and 20 s for CTC, respectively, in which 2 and 3 as promising fluorescence probes for analytes with detection limits of 1.44 and 0.91 μmoL/L, 3.34 and 0.66 μmoL/L, respectively. The fluorescence sensing mechanism was discussed in detail.

Syntheses, structures and luminescent properties of five new Ag(I)-based coordination polymers

In this work, five Ag(I)-based coordination polymers (CPs), namely, [Ag(HL)(H2L)]n (1), [Ag(HL)(2,2′-bpy)(H2O)0.5] (2), [Ag(HL)(phen)(H2O)0.5] (3), {[Ag2(HL)2(4,4′-bpy)(H2O)2]∙H2O} (4) and [Ag(HL)(thpy)]n (5), were synthesized under hydrothermal conditions (H2L = 1-(3-carboxybenzyl)-1H-pyrazole-4-carboxylic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine and thpy = 2-(2-thienyl)pyridine). These coordination polymers were characterized by single-crystal X-ray diffraction, elemental analyses, infrared spectroscopy, thermogravimetric analyses and powder X-ray diffraction. Compound 1 displays a one-dimensional (1D) chain structure which can be further extended into a three-dimensional (3D) supramolecular structure via intermolecular hydrogen bond. In compounds 2 and 3, the binuclear zero dimensional (0D) units are extended to 3D supramolecular frameworks by intermolecular hydrogen bond and π–π stacking interaction. In compound 4, the 0D units constructed by HL− anions, 4,4′-bpy and metal ions are expanded to form a two-dimensional (2D) supramolecular network. Compound 5 shows a different 2D supramolecular structure extended from 1D chain by intermolecular hydrogen bond. The results suggest that organic ligand plays a key role in the formation of the final structures. The solid-state luminescent properties of compounds 1–5 were studied in detail. The results show that the luminescent color of compounds 1–5 can be tunable by varying excitation wavelengths.

Enhanced photocatalytic degradation performance of new and stable 2D/3D Ln-MOFs for tetracycline under visible light

Rational design of lanthanide metal-organic frameworks (Ln-MOFs) with high stability is of great significance for multifunctional applications. Ln-MOFs have attracted extensive attention in the field of photocatalysis due to their large specific surface area and strong visible light efficiency. In this paper, two 2D/3D Ln-MOFs with different spatial configurations have been successfully synthesized under solvothermal conditions, namely [La(HL)(H2O)]n·3H2O (1), [Er(HL)·3/2(H2O)]n·3/2H2O (2), where H4L = 5-(bis(3-carboxybenzyl)amino)isophthalic acid. Their structures were determined by X-ray single crystal diffraction analysis, and further characterized by XRD analysis and IR spectroscopy. The complex 1 shows layered structure, which extends into a three-dimensional (3D) supramolecular network by π-π interactions, the complex 2 exhibit 3D network structures with a Schläfli symbol of 412·63 topologies, respectively. BET test results showed that there were carboxylic acid groups without coordination in the structure of complex 1, with abundant active sites and higher adsorption activity than complex 2, which would promote the effective contact and reaction between the photocatalyst and tetracycline (TC), thus improving the photocatalytic efficiency of complex 1. Under visible light irradiation, complex 1 showed good photocatalytic degradation of TC, and the degradation rate of TC could reach 75.54% under 120 min. This can be attributed to the effective separation of photogenerated electron-hole pairs and adsorption properties of complex 1. This study provides a new idea for MOFs as an efficient photocatalyst to degrade antibiotic pollutants.

Five new luminescent Pb(II) and Ag(I) coordination polymers based on 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and different neutral ligands

Five new coordination polymers (CPs), namely {Pb1.5(L)} (1), {Pb3(L)2(2,2′-bpy)·2·5H2O} (2), {[Pb(HL)(phen)]·H2O} (3), {Ag2(HL)} (4) and {Ag(H2L)(phen)} (5), have been constructed by using 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid (H3L) as an organic ligand. Compound 1 reveals a three-dimensional (3D) (4,6,7)-connected framework with the point symbol of {410·65}{46}2{48·613}2. Compound 2 exhibits a novel (3,6)-connected 3D framework based on a trinuclear Pb(II) cluster with point symbol {42.6}2{44.62.88.10}. Compound 3 is a 1D chain that is further assembled into a 3D supramolecular framework by hydrogen-bonds. Compound 4 shows a (3,6)-connected 3D structure based on a tetranuclear Ag(I) cluster with {4·62}2{42·610·83} topology. Compound 5 is a 0D structure, and can be further expanded into a 3D supramolecular network by various weak interactions. The solid-state luminescent spectra have been measured at room temperature. The results show that compounds 1–5 exhibit strong luminescent emission in the visible region, and can be tunable by varying excitation wavelengths.

A novel Ag3L2 coordination cage derived from a tripodal oxazoline ligand: synthesis, structure and catalysis

Coordination cages have attracted considerable attention recently due to the well-defined cavities and varied potential applications in different fields. In this work, a new tripodal oxazoline-based ligand with C3 symmetry, tris(4-(4,5-dihydrooxazol-2-yl)phenyl)amine (TOPA), was synthesized and employed to constitute coordination cage compounds. By the reaction of TOPA and AgPF6 at room temperature, a novel M3L2-type crystalline coordination cage complex was obtained with the formula of {[Ag3(TOPA)2]·(PF6)3}(1). In this complex, the adjacent two ligands coordinated with three Ag+ ions to form a coordination cage and these cages further generate the three-dimensional (3D) supramolecular networks through noncovalent interactions including hydrogen bond, C-H…π and F…Ag interactions. Moreover, cage complex 1 exhibited good catalytic performance in the cyclopropanation of styrene with methyl 2-diazo-2-(4-methoxyphenyl)acetate.

A combined experimental and theoretical studies of two new Co(II)–PDA complexes: Unusual 2D and 3D supramolecular networks [PDA = 2,6-pyridinedicarboxylic acid

Two new Co(II) complexes, {[Co(2,6-pydc)2]·[Co(4,4′-tmdpy)(H2O)4]n·2H2O}(1) and {2[Co(2,6-pydc)2]2-·[2(4,4′-bpy]2+·10(H2O)·O}(2) [2,6-pydc = 2,6-pyridinedicarboxylic acid, 4,4′-tmdpy = 4,4′-trimethylenedipyridine, 4,4′-bpy = 4,4′-Bipyridine] were designed, synthesized, and characterized using elemental analysis, spectroscopic techniques, and single-crystal X-ray diffraction analysis. For complex (1), hydrogen bonding, π⋅⋅⋅π and lone pair (l.p.)···π interactions produce supramolecular assemblies, whereas for complex (2), hydrogen bonding, π⋅⋅⋅π, π⋅⋅⋅π+, π+⋅⋅⋅π, l.p···π play the pivotal role in building final solid-state structure. Complex (1) exhibits a unique 3D supramolecular architecture generated through π⋅⋅⋅π and l.p···π interactions. Complex (2) also exhibits a unique (l.p···π/π⋅⋅⋅π+/π+⋅⋅⋅π/π⋅⋅⋅π/π⋅⋅⋅π+/π+⋅⋅⋅π/π⋅⋅⋅l.p)n self-assembly. The noncovalent interactions were characterized through Bader’s quantum theory of “Atoms In Molecules” (QTAIM). Evaluation of topological parameters at (3, –1) bond critical points (BCPs) confirmed the 'closed-shell' nature of the intermolecular interactions. Furthermore, the theoretical “Noncovalent Interaction” (NCI) plot index was used to characterize noncovalent interactions.

Synthesis, Crystal Structure, and Luminescent Sensing Properties of a Supramolecular 3D Zinc(II) Metal–Organic Framework with Terephthalate and Bis(imidazol-1-yl)methane Linkers

Supramolecular 3D Zn(II) coordination polymer {[Zn(bim)(bdc)]⋅0.8DMF⋅0.4EtOH⋅0.1H2O }n (Zn-MOF), constructed from Zn2+ ions, bis(imidazol-1-yl)methane (bim) and terephthalate (bdc2−) anions, was synthesized and structurally characterized. Zn-MOF crystallizes in the tetragonal crystal system, space group P42/n. Each Zn(II) ion coordinates two neutral bim molecules in a bridging bidentate coordination mode via nitrogen atoms at position 3 of the imidazole rings and two bdc2− anions, with monodentate coordination of the carboxylate group for one of them and bidentate coordination for another. Zn(II) cations are in a distorted square pyramidal ZnN2O3 coordination environment. Metal cations are alternately linked by the bim and bdc2− ligands, forming a two-dimensional layered structure along the crystallographic plane ab. As a result of layer interpenetration, a supramolecular 3D network is formed. Zn-MOF demonstrated blue (aquamarine) emission with a maximum at 430 nm upon excitation at 325 nm. The luminescence lifetime of 6 ns is characteristic for ligand-centered fluorescence. The luminescent sensing properties of Zn-MOF in ethanol suspension toward inorganic cations and anions were evaluated and an emission quenching response was observed for Fe3+ and chromate/dichromate ions. Photoinduced electron transfer from Zn-MOF to Fe3+ was elucidated as a possible quenching mechanism on the basis of DFT calculations.

Synthesis, structure characterization and antitumor activities of copper and cobalt thiocyanate complexes with 3-acetlpyridine ligand

Complexes of [Cu(SCN)2(3-Acpy)2], (1) and [Co(SCN)2(H2O)2(3-Acpy)2], (2) were synthesized at ambient temperature by adding an aqueous solution of copper(II) or cobalt(II) chloride to H2O/CH3CN solution of 3-acetlpyridine (3-Acpy) and potassium thiocyanate. Elemental analysis, FT-IR and UV–vis spectra were used to comprehensively characterize complexes 1 and 2. Single crystal X-ray diffraction was used to analyze the crystal structure of complexes 1 and 2. In complex 1, the copper is bonded to two 3-Acpy ligands and two thiocyanates groups in trans mode giving square planer geometry. While, in complex 2, the cobalt ion is coordinated to two water molecules, two 3-Acpy ligands and two thiocyanates ions in trans mode giving an octahedral structure. Through hydrogen bonding, the discrete units of complexes 1 and 2 extend to form a 3D supramolecular network. Additionally, the luminescence spectra of complexes 1 and 2 were investigated. Complexes 1 and 2 were evaluated to determine whether they were able to inhibit the growth of liver cancer (HepG2 cells) and breast cancer (MCF-7 cells). Complex 1 exhibits lower IC50 values than complex 2 against both of the two human cell lines. In HepG2 cells treated with complexes 1 and 2 at dosages roughly half of the IC50, apoptosis of complexes 1 and 2 is triggered by 18% and 22%, respectively. It was found that copper complex 1 has a greater cytotoxic effect on MCF-7 and influences on late apoptosis of HepG2.