Supramolecular Chirality in Organo‐, Hydro‐, and Metallogels Derived from Bis‐amides of L‐(+)‐Tartaric Acid: Formation of Highly Aligned 1D Silica Fibers and Evidence of 5‐c Net SnS Topology in a Metallogel Network

A series of bis‐amides derived from L ‐(+)‐tartaric acid was synthesized as potential low‐molecular‐weight gelators. Out of 14 bis‐amides synthesized, 13 displayed organo‐, hydro‐, and ambidextrous gelation behavior. The gels were characterized by methods including circular dichroism, differential scanning calorimetry, optical and electron microscopy, and rheology. One of the gels derived from di‐3‐pyridyltartaramide ( D‐3‐PyTA ) displayed intriguing nanotubular morphology of the gel network, which was exploited as a template to generate highly aligned 1D silica fibers. The gelator D‐3‐PyTA was also exploited to generate metallogels by treatment with various Cu^II/Zn^II salts under suitable conditions. A structure–property correlation on the basis of single‐crystal and powder X‐ray diffraction data was attempted to gain insight into the structures of the gel networks in both organo‐ and metallogels. Such study led to the determination of the gel‐network structure of the Cu^II coordination‐polymer‐based metallogel, which displayed a 2D sheet architecture made of a chloride‐bridged double helix that resembled a 5‐c net SnS topology.     

Metal(II) Ion Complexes with 5‐(Pyrazin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione; Synthesis,Structural Characterization,Acid‐base,and Complexing Properties in Solution

The study reports the synthesis of complexes Co(HL)Cl₂ ( 1 ), Ni(HL)Cl₂ ( 2 ), Cu(HL)Cl₂ ( 3 ), and Zn(HL)₃Cl₂ ( 4 ) with the title ligand, 5‐(pyrazin‐2‐yl)‐1,2,4‐triazole‐5‐thione (HL), and their characterization by elemental analyses, ESI‐MS (m/z), FT‐IR and UV/Vis spectroscopy, as well as EPR in the case of the Cu^II complex. The comparative analysis of IR spectra of the metal ion complexes with HL and HL alone indicated that the metal ions in 1 , 2 , and 3 are chelated by two nitrogen atoms, N(4) of pyrazine and N(5) of triazole in the thiol tautomeric form, whereas the Zn^II ion in 4 is coordinated by the non‐protonated N(2) nitrogen atom of triazole in the thione form. pH potentiometry and UV/Vis spectroscopy were used to examine Co^II, Ni^II, and Zn^II complexes in 10/90 (v/v) DMSO/water solution, whereas the Cu^II complex was examined in 40/60 (v/v) DMSO/water solution. Monodeprotonation of the thione triazole in solution enables the formation of the L:M = 1:1 species with Co^II, Ni^II and Zn^II, the 2:1 species with Co^II and Zn^II, and the 3:1 species with Zn^II. A distorted tetrahedral arrangement of the Cu^II complex was suggested on the basis of EPR and Vis/NIR spectra.     

Metal(II) complexes and metal(II) salts ofN-carbamoylpyrazole: N,O and N,N coordination

Summary Several new coordination compounds are reported withN-carbamoylpyrazole (Hcpz) as the ligand;viz. M(cpz)₂ where M = Cu^II and Ni^II; M(Hcpz)Cl₂ where M = Mn^II, Co^II, Cu^II, Zn^II and Cd^II; M(Hcpz)₂Cl₂ Where M = Fe^II, Co^II and Ni^II: M(Hcpz)₃(BF₄)₂ where M = Fe^II, Co^II, Ni^II, Zn^II and Cd^II; and Cu(Hcpz)₂(BF₄)₂. In the salts, Hcpz is coordinated through the nitrogen atoms of the pyrazole ring and the nitrogen atom of the carbamoyl group. In the Hcpz complexes, coordination takes place through the nitrogen atom of the pyrazole ring and the oxygen atom of the carbamoyl group.     

Experimental and Theoretical Investigation of Vibrational Spectra of Coordination Polymers Based on TCE‐TTF

The room‐temperature infrared and Raman spectra of a series of four isostructural polymeric salts of 2,3,6,7‐tetrakis(2‐cyanoethylthio)‐tetrathiafulvalene (TCE‐TTF) with paramagnetic (Co^II, Mn^II) and diamagnetic (Zn^II, Cd^II) ions, together with BF₄^? or ClO₄^? anions are reported. Infrared and Raman‐active modes are identified and assigned based on theoretical calculations for neutral and ionized TCE‐TTF using density functional theory (DFT) methods. It is confirmed that the TCE‐TTF molecules in all the materials investigated are fully ionized and interact in the crystal structure through cyanoethylthio groups. The vibrational modes related to the C?C stretching vibrations of TCE‐TTF are analyzed assuming the occurrence of electron–molecular vibration coupling (EMV). The presence of the antisymmetric C?C dimeric mode provides evidence that charge transfer takes place between TCE‐TTF molecules belonging to neighboring polymeric networks.     

Synthese,Struktur und EPR‐Untersuchungen von binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))‐Komplexen des CuII,NiII, ZnII,CdII und PdII

Synthesis, Structure and EPR Investigations of binuclear Bis(N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato)) Complexes of Cu^II, Ni^II, Zn^II, Cd^II and Pd^II The synthesis of binuclear Cu^II‐, Ni^II‐, Zn^II‐, Cd^II‐ and Pd^II‐complexes of the quadridentate ligand N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and the crystal structures of the Cu^II‐ and Ni^II‐complexes are reported. The Cu^II‐complex crystallizes in two polymorphic modifications: triclinic, (Z = 1) and monoclinic, P2₁/c (Z = 2). The Ni^II‐complex was found to be isostructural with the triclinic modification of the copper complex. The also prepared Pd^II‐, Zn^II‐ and Cd^II‐complexes could not be characterized by X‐ray analysis. However, EPR studies of diamagnetically diluted Cu^II/Pd^II‐ and Cu^II/Zn^II‐powders show axially‐symmetric g and A ^Cu tensors suggesting a nearly planar co‐ordination within the binuclear host complexes. Diamagnetically diluted Cu^II/Cd^II powder samples could not be prepared. In the EPR spectra of the pure binuclear Cu^II‐complex exchange‐coupled Cu^II‐Cu^II pairs were observed. According to the large Cu^II‐Cu^II distance of about 7,50Å a small fine structure parameter D = 26·10^?4 cm^?1 is observed; T‐dependent EPR measurements down to 5 K reveal small antiferromagnetic interactions for the Cu^II‐Cu^II dimer. Besides of the dimer in the EPR spectra the signals of a mononuclear Cu^II species are observed whose concentration is T‐dependent. This observation can be explained assuming an equilibrium between the binuclear Cu^II‐complex (Cu^II‐Cu^II pairs) and oligomeric complexes with “isolated” Cu^II ions.     

Proton‐Conducting Supramolecular Metallogels from the Lowest Molecular Weight Assembler Ligand: A Quote for Simplicity

Oxalic acid has been proven to be the lowest molecular weight organic ligand able to form robust supramolecular metallogel networks in the presence of metal salts. In particular, two novel multifunctional metallogels were readily prepared at room temperature by simple mixing of stock solutions of Cu^II acetate monohydrate or Cu^II perchlorate hexahydrate and oxalic acid dihydrate. Formation of different polymorphs and unprecedented proton conduction under anhydrous conditions were also demonstrated with some of these materials.     

Water‐Exchange Mechanism for Zinc(II), Cadmium(II), and Mercury(II) Ions in Water as Studied by Umbrella‐Sampling Molecular‐Dynamics Simulations

Umbrella‐sampling molecular‐dynamics simulations were performed to investigate the water‐exchange reactions of zinc(II), cadmium(II), and mercury(II) ions in aqueous solution. The dissociation of a coordinating water molecule to the M? O distance at 3.34, 3.16, and 3.26 Å for Zn^II, Cd^II, and Hg^II, respectively, leads the system to a transition state. For Zn^II, the first hydration shell is occupied by five spectator water molecules in the transition state, indicating that the water‐exchange reaction proceeds via a dissociative mode of activation. In contrast, the number of spectator water molecules of 5.85 and 5.95 for Cd^II and Hg^II, respectively, suggests an associative exchange for these larger metal ions. The average M? O distance of the spectator molecules is shortened by 0.06 Å for the dissociative exchange of Zn^II, while it is elongated by 0.04 and 0.03 Å for Cd^II and Hg^II, respectively. The water‐exchange rate constants of 4.1×10⁸, 6.8×10⁸, and 1.8×10⁹ s^?1 are estimated for Zn^II, Cd^II, and Hg^II, respectively, at 298 K in terms of the transition‐state theory based on the assumption of a transmission coefficient of unity.     

Structural Variety of Cobalt(II), Nickel(II), Zinc(II), and Cadmium(II) Complexes with 4,4′‐Azopyridine: Synthesis,Structure and Luminescence Properties

Self‐assembled bi‐ and polymetallic complexes of Co^II, Ni^II, Zn^II, and Cd^II were obtained by the reaction of 4,4′‐azopyridine (azpy) with metal tri‐tert‐butoxysilanethiolates (Co, 1 ; Cd, 2 ), acetylacetonates (Ni, 3 ; Zn, 4 ), and acetates (Cd, 5 ). All compounds were characterized by single‐crystal X‐ray structure analysis, elemental analysis, FTIR spectroscopy, and thermogravimetry. Complexes 1 , 2 and 4 , 5 exhibit diverse structural conformations: 1 is bimetallic, 2 and 4 are 1D coordination polymers, and 5 is a 2D coordination framework formed from bimetallic units. The obtained complexes contain metal atoms bridged by a molecule of azpy. The luminescent properties of 1–5 were investigated in the solid state.     

Pyrazolato and related anions. Part V. Transition metal salts of 4-methylpyrazole

Summary Cd^II, Zn^II, Co^II, Ni^II, Cu^II and Ag^I salts of 4-methylpyrazole have been synthesized and compared with those of 3(5)-methylpyrazole and 3,5-dimethylpyrazole. The compounds were characterized and identified by vibrational spectra, ligand-field spectra and chemical analyses. The pyrazolate ion acts as a bidentate ligand in all cases. Tetrahedral and square-planar coordinations have been observed. Tentative assignments of the vibrational spectra of salts and neutral ligand have been made.     

Entropy‐Driven Mechanochemical Synthesis of Polymetallic Zeolitic Imidazolate Frameworks for CO2 Fixation

High‐entropy materials refer to a kind of materials in which five or more metal species were incorporated deliberately into a single lattice with random occupancy. Up to now, such a concept has been only restricted to hard materials, such as high‐entropy alloys and ceramics. Herein we report the synthesis of hybrid high‐entropy materials, polymetallic zeolitic imidazolate framework (also named as high‐entropy zeolitic imidazolate framework, HE‐ZIF), via entropy‐driven room‐temperature mechanochemistry. HE‐ZIF contains five metals including Zn^II, Co^II, Cd^II, Ni^II, and Cu^II which are dispersed in the ZIF structure randomly. Moreover, HE‐ZIF shows enhanced catalytic conversion of CO₂ into carbonate compared with ZIF‐8 presumably a result of the synergistic effect of the five metal ions as Lewis acid in epoxide activation.     

Complexes of Crown Ether‐Containing N‐Phosphorylated Thioamides and Thioureas with CoII,ZnII and PdII Cations

The reaction of the potassium salts of N‐phosphorylated thioureas [4′‐benzo‐15‐crown‐5]NHC(S)NHP(Y)(OiPr)₂ (Y = S, HL^I ; Y = O, HL^II ) with Zn^II and Co^II cations in aqueous EtOH leads to complexes of formulae Zn(L^I,II‐S,Y)₂ (Y = S, 1 ; Y = O, 2 ) and Co(L^I‐S,S′)₂ ( 3 ), while interaction of the potassium salt of N‐phosphorylated thioamide [4′‐benzo‐15‐crown‐5]C(S)NHP(O)(OiPr)₂ ( HL^III ) with Zn^II in the same conditions leads to the complex Zn(HL^III)(L^III‐S,O)₂ ( 4 ). The reaction of the potassium salt of crown ether‐containing N‐phosphorylated bis‐thiourea N,N′‐[C(S)NHP(O)(OiPr)₂]₂‐1,10‐diaza‐18‐crown‐6 ( H₂L ) with Co^II, Zn^II and Pd^II cations in anhydrous CH₃OH leads to complexes M₂(L‐O,S)₂ (M = Co, 5 ; Zn, 6 ; M = Pd, 7 ). Thioamide HL^III was investigated by single‐crystal X‐ray diffraction.     

Exploring Orthogonal Hydrogen Bonding towards Designing Organic‐Salt‐Based Supramolecular Gelators: Synthesis,Structures, and Anticancer Properties

A series of primary ammonium monocarboxylate (PAM) salts derived from β‐alanine derivatives of pyrene and naphthalene acetic acid, along with the parent acids, were explored to probe the plausible role of orthogonal hydrogen bonding resulting from amide???amide and PAM synthons on gelation. Single‐crystal X‐ray diffraction (SXRD) studies were performed on two parent acids and five PAM salts in the series. The data revealed that orthogonal hydrogen bonding played an important role in gelation. Structure–property correlation based on SXRD and powder X‐ray diffraction data also supported the working hypothesis upon which these gelators were designed. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) and cell migration assay on a highly aggressive human breast cancer cell line, MDA‐MB‐231, revealed that one of the PAM salts in the series, namely, PAA.B2 , displayed anticancer properties, and internalization of the gelator salt in the same cell line was confirmed by cell imaging.     

The synthesis,characterization and spectral studies of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl]amino}butyl) N′,N′-dihydroxyethanediimidamide

Co^II, Ni^II, Cu^II, Zn^II and Cd^II complexes of N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl)methyl]amino}butyl)N′,N′-dihydroxyethanediimidamide (LH₂) were synthesized and characterized by elemental analyses, IR, ¹H- and ¹³C-NMR spectra, electronic spectra, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analyses (TGA). The Co^II, Ni^II and Cu^II complexes of LH₂ were synthesized with 1?:?2 metal ligand stoichiometry. Zn^II and Cd^II complexes with LH₂ have a metal ligand ratio of 1?:?1. The reaction of LH₂ with Co^II, Ni^II, Cu^II, Zn^II and Cd^II chloride give complexes Ni(LH)₂, Cu(LH)₂, Zn(LH₂)(Cl)₂, Cd(LH₂)(Cl)₂, respectively.     

Homo‐ and Heteronuclear Compounds with a Symmetrical Bis‐hydrazone Ligand: Synthesis,Structural Studies,and Luminescent Properties

Nine new coordination compounds have been synthesized by the reaction of salts of bivalent metal ions (a=Zn^II, b=Cu^II, c=Ni^II, d=Co^II) with the bis(benzoylhydrazone) derivative of 4,6‐diacetylresorcinol (H₄L). Three kinds of complexes have been obtained: homodinuclear compounds [M₂(H₂L)₂]?nH₂O ( 1 a , 1 b , 1 c , and 1 d ), homotetranuclear compounds [M₄(L)₂]?n(solv) ( 2 a and 2 c ), and heterotetranuclear compounds [Zn₂M₂(L)₂]?n(solv) ( 2 ab , 2 ac , and 2 ad ). The structures of the free ligand H₄L?2 DMSO and its complexes [Zn₂(H₂L)₂(DMSO)₂] ( 1 a* ), [Zn₄(L)₂(DMSO)₆] ( 2 a* ), and [Zn_0.45Cu_3.55(L)₂(DMSO)₆]?2 DMSO ( 2 ab* ) were elucidated by single‐crystal X‐ray diffraction. The ligand shows luminescence properties and its fluorimetric behavior towards M^II metals (M=Zn, Cu, Ni and Co) has been studied. Furthermore, the solid‐state luminescence properties of the ligand and compounds have been determined at room temperature. ¹H NMR spectroscopic monitoring of the reaction of H₄L with Zn^II showed the deprotonation sequence of the OH/NH groups upon metal coordination. Heteronuclear reactions have also been monitored by using ESI‐MS and spectrofluorimetric techniques.     

Trinuclear Cobalt(II) and Zinc(II) Salamo‐type Complexes: Syntheses,Crystal Structures,and Fluorescent Properties

Two trinuclear Co^II and Zn^II complexes, [(CoL)₂(OAc)₂Co] and [(ZnL)₂(OAc)₂Zn], with an asymmetric Salen‐type bisoxime ligand [H₂L = 4‐(N,N‐diethylamine)‐2,2′‐[ethylenediyldioxybis(nitrilomethylidyne)]diphenol] were synthesized and characterized by elemental analyses, IR, UV/Vis, and fluorescent spectroscopy. The crystal structures of the Co^II and Zn^II complexes were determined by single‐crystal X‐ray diffraction methods. The Co^II atom is pentacoodinated by N₂O₂ donor atoms from the (L)^2– unit and one oxygen atom from the coordinated acetate ion, resulting in a trigonal bipyramid arrangement. With the help of intermolecular hydrogen bonding C–H ··· O and C–H ··· π interactions, a self‐assembled continual zigzag chain‐like supramolecular structure is formed. The Zn^II atom is pentacoodinated by N₂O₂ donor atoms from the (L)^2– unit and one oxygen atom from the coordinated acetate ion, resulting in an almost regular trigonal bipyramid arrangement. A self‐assembled continual 1D supramolecular chain‐like structure is formed by intermolecular hydrogen bonding C–H ··· O and C–H ··· π interactions. Additionally, the photophysical properties of the Co^II and Zn^II complexes were discussed.     

Rationally Developed Organic Salts of Tolfenamic Acid and Its β‐Alanine Derivatives for Dual Purposes as an Anti‐Inflammatory Topical Gel and Anticancer Agent

A new series of primary ammonium monocarboxylate (PAM) salts of a nonsteroidal anti‐inflammatory drug (NSAID), namely, tolfenamic acid ( TA ), and its β‐alanine derivatives were generated. Nearly 67 % of the salts in the series showed gelling abilities with various solvents, including water (biogenic solvent) and methyl salicylate (typically used for topical gel formulations). Gels were characterized by rheology, electron microscopy, and so forth. Structure–property correlations based on single‐crystal and powder XRD data of several gelator and nongelator salts revealed intriguing insights. Studies (in vitro) on an aggressive human breast cancer cell line (MDA‐MB‐231) with the l ‐tyrosine methyl ester salt of TA ( S7 ) revealed that the hydrogelator salt was more effective at killing cancer cells than the mother drug TA (3‐(4,5‐ di methyl thiazol ‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay); displayed better anti‐inflammatory activity compared with that of TA (prostaglandin E₂ assay); could be internalized within the cancer cells, as revealed by fluorescence microscopy; and inhibited effectively migration of the cancer cells. Thus, the easily accessible ambidextrous gelator salt S7 can be used for two purposes: as an anti‐inflammatory topical gel and as an anticancer agent.     

Synthesis,Crystal Structures,and Properties of Copper(II), Zinc(II), and Cadmium(II) Coordination Polymers Based on 5‐Nitro‐isophthalate and 1,2‐(2‐Pyridyl)‐1,2,4‐triazole

Three coordination polymers, namely {[Cu(5‐nipa)(L²²)](H₂O)₂}_n ( 1 ), [Zn(5‐nipa)(L²²)(H₂O)]_n ( 2 ), and {[Cd₂(5‐nipa)₂(L²²)(H₂O)₃](H₂O)_3.6}_n ( 3 ), were prepared under similar synthetic method based on 1,2‐(2‐pyridyl)‐1,2,4‐triazole (L²²) and ancillary ligand 5‐nitro‐isophthalic acid (5‐H₂nipa) with Cu^II, Zn^II, and Cd^II perchlorate, respectively. All the complexes were characterized by IR spectroscopy, elemental analysis, and powder X‐ray diffraction (PXRD) patterns. Single‐crystal X‐ray diffraction indicates that complexes 1 and 2 show similar 1D chain structures, whereas complex 3 exhibits the 2D coordination network with hcb topology. The central metal atoms show distinct coordination arrangements ranging from distorted square‐pyramid for Cu^II in 1 , octahedron for Zn^II in 2 , to pentagonal‐bipyramid for Cd^II in 3 . The L²² ligand adopts the same (η³,μ₂) coordination fashion in complexes 1 – 3 , while the carboxyl groups of co‐ligand 5‐nipa^2– adopt monodentate fashion in 1 and 2 and bidentate chelating mode in 3 . These results indicate that the choice of metal ions exerts a significant influence on governing the target complexes. Furthermore, thermal stabilities of complexes 1 – 3 and photoluminescent properties of 2 and 3 were also studied in the solid state.     

Synthesis,Crystal Structure and Photoluminescence Property of Zinc(II), Cadmium(II), and Lead(II) Complexes with Bidentate Ligand: 1‐(1‐Imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB)

Assembly of bidentate ligand 1‐(1‐imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB) with varied metal salts of Zn^II, Cd^II and Pb^II provide three new complexes, [Zn(IIMB)₂](ClO₄)₂·2H₂O ( 1 ), [Cd(IIMB)₂(SCN)₂] ( 2 ) and [Pb(IIMB)₂(SCN)](SCN) ( 3 ). Single crystal X‐ray diffraction studies revealed that complexes 1 and 2 display a similar one‐dimensional double stranded chain structure, while complex 3 is a slight distorted rhombohedral grid network with (4,4) topology. The results indicate that the coordination geometry of the metal ion and the counter anion have great impact on the structure of the complexes. In addition, the photoluminescence properties of ligand IIMB and complexes 1 – 3 were studied in the solid state at room temperature.     

Synthesis,characterization and antimicrobial activity of macrocylic phenoxo-bridged di- and tetra-nuclear complexes from <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]succinoyl/sebacoyldicarboxamides

Macrocyclic ligands N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]succinoyl dicarboxamide (H₂L¹) and N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]sebacoyl dicarboxamide (H₂L²) were synthesized and characterized by various spectral techniques. Macrocyclic di- and tetra-homonuclear phenoxo bridged Cu^II, Co^II, Ni^II, Zn^II, Cd^II and Hg^II complexes have been synthesized through the template method by using the precursors 2,6-diformyl-4-methylphenol, succinoyldihydrazide/ sebacoyldihydrazide and respective metal chlorides in 2:2:2/2:2:4 ratio respectively. The synthesized complexes were characterized by i.r., n.m.r., u.v.-vis., FAB-mass, e.s.r., magnetic susceptibility and elemental analyses data. The elemental analyses and FAB-mass spectral data have justified the dinuclear and tetra nuclear structure for the complexes of the ligands H₂L¹ and H₂L² respectively. The observed low magnetic moment values revealed the existence of antiferromagnetic spin exchange interaction operating between the two metal centers. Electronic data suggested the octahedral geometry for Ni^II complexes and square pyramidal geometry for Cu^II, Co^II, Zn^II, Cd^II and Hg^II complexes of both the ligands. The Cu^II, Co^II and Zn^II complexes of both the ligands have shown good antifungal activity against Aspergillus niger and Fusarium oxysporum and medium to weak antibacterial activity against Escherichia coli and Staphylococcus aureus when compared to the standard drugs Grisefulvin and Ciprofloxacin respectively.