Bipy Ligands Research Articles

Synthesis, characterization, and antimicrobial properties of two new Bis(oxalato)metalate(III) hybrid salts with 2,2’-bipyridinium cation

Two new isostructural hybrid salts, 2,2′-bipyridinium (2,2′-bipyridine-к2N1, N2)bis[oxalato(2-)-к2O1,O2]metalate(III)] hydrate (MIII = CrIII and CoIII), (C10H9N2)[Cr(C2O4)2(C10H8N2)]·H2O (1) and (C10H9N2)[Co(C2O4)2(C10H8N2)]·H2O (2), (C10H8N2 or bipy = 2,2′-bipyridine and (C10H9N2)+ or bipyH+ = 2,2′-bipyridinium) were prepared in H2O/EtOH (2:1) solution by slow evaporation at room temperature. They were characterized by FTIR and UV–Vis spectroscopies, elemental, thermal, single-crystal X-ray diffraction, and Hirshfeld surface analyses. Both compounds crystallize in the monoclinic P21/c space group and are made up of 2,2′- bipyridinium cations, water molecules, and the mononuclear anionic tectons: 2,2′-bipyridinebis(oxalato)chromate(III) for 1 or 2,2′-bipyridinebis(oxalato)cobaltate(III) for 2. The CrIII and CoIII environments in 1 and 2 are distorted octahedral geometries with two bidentate oxalate groups and one bidentate bipy ligand. The MIII ̶ O and MIII ̶ N bond distances vary in the ranges 1.942(1) - 1.967(1) Å and 2.055(2) - 2.066(1) Å respectively. The cohesion of both structures is reinforced by intermolecular N H···O, O H···O and C(π) H···O hydrogen bond interactions which connect the ionic entities and the water molecules into 3-D supramolecular frameworks. All the oxygen atoms are involved in the hydrogen bonding system. The H···O/O···H, H···H, H···C/ C···H, C···C and O···C/C···O contacts contribute with 38.6, 31.1, 14.4, 7.1 and 4.2 % respectively to the Hirshfield surface (HS) of 1 and close values are found for 2. Thermal studies reveal that 1 and 2 are thermally stable up to 130 °C and 110 °C, respectively. The ligands, metal salt, and complexes were evaluated for their antimicrobial activities in vitro against seven pathogens (four bacteria and three fungi species). The complexes have an activity higher than those of the metal salts and the oxalate ligand but lower than those of the 2,2′-bipyridine ligand. The cobalt (III) complex 2 shows a higher activity compared to the chromium(III) complex 1. These results illustrate the fact that an appropriate combination of ligands and metal ions can lead to complex salts with enhanced biological activities.

Synthesis, characterization, crystal structures and catalytic activity of hydrogen bond mediated 2D and 3D-copper(II) coordination networks based on 2-aminoterepthalic acid and 5-aminoisopthalic acid

Two new copper(II) compounds [Cu2(2-NH2BDC)2(bipy)2(H2O)4] (1) and [Cu2(µ2OH)2(5-aip)(bipy)2(H2O)].5H2O (2) have been synthesized and characterized by elemental analyses, IR, thermogravimetric analysis, and electronic absorption spectroscopy. Molecular structures of compounds 1 and 2 were determined crystallographically. Single crystal X-ray studies show that the coordination network 1 is a centrosymmetrical dimeric unit with the 2-aminoterephthalate ligand bridging the two copper atoms. Each CuII atom is hexacoordinated, residing in an octahedral environment, surrounded by one oxygen and one nitrogen atoms from 2-aminoterephthalate ligand and two nitrogen atoms from one bipy ligand and two water molecules to give a CuO3N3 segmentand generate the an infinite three-dimensional (3D) supramolecular structure resulting from CH•••O interactions between adjacent dimer molecules running parallel to the a axis. In compound 2, each CuII atom is pentacoordinated, residing in a square pyramidal geometry and generate an infinite two-dimensional (2D) supramolecular structure resulting from CH•••O, NH•••O and OH•••O hydrogen bond interactions. The coordination network 1 and 2, on pyrolyzing, yielded copper oxide nanoparticles, which have been characterized by TEM and powder X-ray diffraction. The catalytic properties of the resulting copper oxide nanoparticles have also been studied for CN cross-coupling reactions with aryl halides. The CN coupling products were obtained in 70–99 % yields.

A luminescent binuclear Cu(I) complex constructed by bipyridine, TD-DFT calculation, and its fluorescent sensing properties for VOCs

The design and research of materials with strong luminescence and fluorescence sensing for the detection of volatile organic compounds (VOCs) are of great significance and challenge. Herein, we report a binuclear Cu(I) complex, [Cu2(POP)2(MeCN)2(4,4′-bipy)](PF6)2 (2), which is synthesized rationally through a substitution reaction between complex [Cu(POP)(4-PBO)(MeCN)](PF6) (1) and 4,4′-bipy lignand (POP is bis[2-(diphenylphosphino)phenyl]ether, 4,4′-bipy is bipyridine, 4-PBO is 2-(4′-pyridyl)-benzoxazole). The complex 2 was characterized by single-crystal X-ray diffraction as an isolated binuclear structure constructed by a bridged 4,4′-bipy ligand. Under UV irradiation, both the powder and doped thin film of 1 and 2 exhibit broadband photoluminescence emission. The TD-DFT calculation reveals the details of the electronic transitions corresponding to the light absorption and emission of the two complexes, and also illustrates that the improved luminescence of 2 compared to 1 is due to the T1 excited state transforms from a localized transition to a charge transfer transition similar to the S1 excited state and the extremely small energy gap ΔE(S1-T1) value of 0.09 eV (2). Based on these complexes, fluorescent test strips were developed. It is gratifying to find that the test strip based 2 shows a distinguishable fluorescence response behavior to a variety of VOCs. Especially, the test strip showed a rapid quenching fluorescence response to acetophenone, and a rapid quenching followed by rapid enhancement fluorescence response to acetonitrile. Therefore, it can be used for rapid and highly selective fluorescence sensing detection of acetonitrile and acetophenone.

Synthesis and Characterization of Complex Compounds of Cadmium (II) Nitrate, Potassium Thiocyanate, and 2,2-Bipyridine Ligand

A complex compound of a central atom of cadmium(II), potassium thiocyanate, and a 2,2'-bipy ligand with a stoichiometric ratio of 1:2:2 has never been reported. The aim of this research is to determine the coordination pattern of the 2,2'-bipy ligand and thiocyanate ion and the stability of the compounds formed. Synthesis of complex compounds was carried out using the direct reaction method, characterization of the complex compounds produced using the melting point test, FTIR analysis, SEM-EDX analysis, DHL test, thiocyanate ion qualitative test, and Gaussian 09W analysis. This synthesis produces a block-shaped colorless complex compound with a melting point of 159-161°C and has a distorted tetrahedral geometry around the central cadmium(II) atom and a free energy of -740 kJ/mol and a free energy per bond of -25 kJ/mol.

Tuning of the photophysical and electrochemical properties of ruthenium(II) phthalocyaninates by variation of axial ligands

A series of mononuclear ruthenium(II) tetra-tert-butyl-phthalocyaninates bearing axial N-donor ligands [tBu4PcRu]L2 (L = trimethylamine, pyrazine, 4,4′-bipyridine and N-methyl-4,4′-bipyridinium iodide) as well as the binuclear complex [tBu4PcRu]2(BiPy)3 were synthesized starting from the complex with axially coordinated carbonyl group [tBu4PcRu](CO). All compounds have been characterized by NMR, UV-Vis and cyclic voltammetry. The latter allowed the determination of oxidation and reduction potentials, HOMO-LUMO gaps and revealed the possibility of electropolymerization of BiPy-containing complexes in clear contrast to complexes containing another bidentate ligand – pyrazine. Comparative electrochemical studies of the mono- and binuclear complexes [tBu4PcRu](BiPy)2 and [tBu4PcRu]2(BiPy)3 revealed that the phthalocyanine rings are not conjugated in the binuclear species. The remarkable dependence of singlet oxygen generation from axial ligands in ruthenium phthalocyaninates was observed: the complexes with carbonyl group [tBu4PcRu](CO) and with pyrazine molecules [tBu4PcRu](Pyz)2 show higher 1O2 quantum yields, whereas the complex with axially coordinated molecules of trimethylamine [tBu4PcRu](NMe3)2 and quaternized BiPy ligands [tBu4PcRu](BiPy-Me+)2 have the lowest ability to generate singlet oxygen. The revealed influence of axial ligands on key physicochemical properties paves the way for the design of new ruthenium phthalocyaninates with potential optoelectronic and biomedical applications.

Crystal structures, Hirshfeld surface analysis, thermogravimetric, and spectroscopic properties of three Zn(Ⅱ) complexes bridged by 4,4′-bipy with organic sulfonate anions as counterions

Three Zn(Ⅱ) sulfonate compounds: {[Zn3(Ac)4(4,4′-bipy)4]·2(3-pySO3)·H2O}n (1), {[Zn(4,4′-bipy)(H2O)4]·2(Me-phSO3)}n (2), and {[Zn(4,4′-bipy)(H2O)4]·2(NH2-phSO3)}n (3), were synthesized through solvent diffusion method at room temperature (3-pySO3H = Pyridine-3-Sulfonic acid; Me-phSO3H = P-Toluene Sulfonic acid; NH2-phSO3H = Sulfanilic acid). Single-crystal X-ray diffractions reveal that the crystal structure of compound 1 contains a 2D cationic layer with pseudo-square grid motifs formed by trinuclear Zn(II) units which connected by 4,4′-bipy ligands. Water molecule forms hydrogen bonds with free 3-PySO3− anions which are located in the voids of the cationic grids. Compounds 2 and 3 show isostructural 1D [Zn(4,4′-bipy)(H2O)4]2+ chains with sulfonate anions connected to the chain via hydrogen bonding. The weak interactions in the structures of the three compounds have been assessed using Hirshfeld surface analyses and 2D fingerprint plots. The Hirshfeld surface shows that the most important contributions for the crystal packing are from H···H and H··O/O··H interactions, which indicate dominant van der Waals interactions. In addition, the compounds were investigated by powder X-ray diffraction (PXRD), elemental analyses, UV–vis, FT-IR, solid-state fluorescence spectroscopy, and thermal analyses (TG-DSC).

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C5Me5 and Polyazide Complexes

AbstractExploration of the reduction chemistry of the 2,2’‐bipyridine (bipy) lanthanide metallocene complexes Cp*2LnCl(bipy) and Cp*2Ln(bipy) (Cp* = C5Me5) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*2NdCl(bipy) with excess KC8 resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]2[Cp*Nd(bipy)2], 1, as well as [K(crypt)][Cp*2NdCl2], 2, and the previously reported [K(crypt)][Cp*2Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)2, 3, was also found in an attempt to make Cp*2Lu(bipy) from LuCl3, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)1− ligands in neighboring molecules in the structure of 3 are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*2Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]2[Cp*Eu(THF)(PhNNPh)]2, 4. Attempts to make 4 from the reaction between Cp*2Eu(THF)2 and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]2, 5, which allows direct comparison with the bimetallic Eu(II) complex 4. Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*2Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]2[Cp*Yb(N3)4], 6, or the di‐azido complex [K(crypt)]2[Cp*Yb(N3)2(bipy)], 7 a, depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*2Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]2[Cp*Yb(S4)(S5)], 8 a. In contrast to these reactions that form mono‐Cp* products, reduction of Cp*2Yb(bipy) with 1 equiv. of KC8 in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)4], 9. The (bipy)1− ligands of 9 are arranged in a parallel orientation, as observed in the structure of 3, except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)1− complex, Cp*2Sm(bipy) with 2 equiv. of KC8 in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)2− with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K2(18‐c‐6)2Cp*]2[Cp*2Sm(bipy)]2 ⋅ [K(18‐c‐6)Cp*], 10.

Effect of Auxiliary Ligands on the Architectures of Manganese Complexes Constructed by N-Heterocyclic Ligands: Syntheses, Structures, and Properties

Two manganese complexes based on N-heterocyclic ligands, [Mn(bqdca)(2,2'-bipy)(H2O)2]n (1), Mn0.5(4,4'-bipy) (H2O)2?0.5bqdca?2H2O (2) (H2bqdca = 2, 2'-biquinoline-4, 4'-dicarboxylic acid, 2, 2'-bipy = 2, 2'-bipyridine, 4, 4'-bipy = 4, 4'-bipyridine), have been synthesized by hydrothermal methods based on Pearson?s acid-base theory and structurally characterized. In Complex 1, the Mn ions are bridged by bqdca2- anions to form one-dimensional chains, which are further linked by hydrogen bonds to generate a two-dimensional layered structure. In Complex 2, each Mn ion was coordinated by 4, 4'-bipy and water molecules to generate a mononuclear structure accompanied by bqdca2- anion balancing valences. The intermolecular hydrogen bonds can link them to construct a three-dimensional supramolecular structure. The different structures of Complexes 1 and 2 illustrate the great influence of the N-heterocyclic auxiliary ligands on the self-assembly of coordination architectures. 2,2'- bipy and 4,4'-bipy ligands all act as terminal ligands. In addition, Complexes 1 and 2 exhibit the photoluminescent emission at 455 nm and 463 nm, and 455 nm and 465 nm in the solid state, respectively, which may be attributed to intraligand transitions. The redshifts of Complexes 1 and 2 may be due to the ligand-to-metal charge transfer, comparing to the H2bqdca ligand.. KEYWORDS :Crystal structure, Manganese complex, N-Heterocyclic ligand, Photoluminesce.

Synthesis and Characterization of Complex Compounds of Cadmium (II) Nitrate, Potassium Thiocyanate, and 2,2-Bipyridine Ligand

A complex compound of a central atom of cadmium(II), potassium thiocyanate, and a 2,2'-bipy ligand with a stoichiometric ratio of 1:2:2 has never been reported. The aim of this research is to determine the coordination pattern of the 2,2'-bipy ligand and thiocyanate ion and the stability of the compounds formed. Synthesis of complex compounds was carried out using the direct reaction method, characterization of the complex compounds produced using the melting point test, FTIR analysis, SEM-EDX analysis, DHL test, thiocyanate ion qualitative test, and Gaussian 09W analysis. This synthesis produces a block-shaped colorless complex compound with a melting point of 159-161°C and has a distorted tetrahedral geometry around the central cadmium(II) atom and a free energy of -740 kJ/mol and a free energy per bond of -25 kJ/ mol.

Catalytic oxidation of thymol and carvacrol with Mn(II)-benzoylbenzoate-bipyridine complex

The primary focus of catalytic chemistry is the synthesis of valuable chemicals from cheaper and more abundant substrates. The main objective of catalytic processes is to achieve higher yields at affordable costs under environmentally friendly conditions. Under homogeneous conditions, the synthesized bimetallic Mn(II) complex with (2-benzoylbenzoic acid, bba) and N,N coordinated (2,2-bipyridine, bipy) ligands, [Mn2(μ1,3-(C6H5)CO(C6H4)COO)2(bipy)2].2ClO4 is shown to be an active catalyst for the oxidation of monoterpenes (thymol and carvacrol), using TBHP under mild reaction conditions. The structure of the complex was characterized by single-crystal X-ray diffraction. The six-coordinated Mn(II) centers bridge in a coordination pattern due to the monodentate bonding mode of the carboxylate oxygen atoms of benzoylbenzoate anion. The selectivity of the Mn-catalyst was measured to be 100 % for thymol and carvacrol to thymoquinone. A simple, effective and selective Mn(II)/TBHP/Monoterpene/CH3CN catalyst system was used for the oxidation of thymol (TOF = 2000 h−1, in 15 min) and carvacrol (TOF = 667 h−1, in 45 min.) into a valuable product, thymoquinone (TQ), in acetonitrile at 80 °C.

Application of manganese-based driers in tung oil: drying behavior, paint film properties, and drying mechanism

Organic chelating ligands can enhance the drying efficiency of manganese (Mn2+)-based driers by altering the spatial and electronic properties. However, the correlation between organic chelating ligands and their ability to dry tung oil remains unclear, as well as the underlying mechanism. In this work, the effects of acetylacetone (Hacac), benzimidazole (benz), and 2,2-bipyridine (bipy) ligands on the Mn2+-mediated drying of tung oil were investigated. The curing process of tung oil was studied by Fourier-transform infrared (FTIR) spectroscopy and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopy. The results showed that strongly-electronegative coordination atoms improved the drying activity of Mn2+. In addition to the type of coordination atoms, their quantity also promoted paint film drying and property improvements. Compared with the pure tung oil, under the action of the drier with the most coordination atoms, the paint film drying time was shortened by 86.58 h, and the hardness, flexibility, and scratch resistance were improved by 3.98%, 16%, and 200 g, respectively. This study helps understand the mechanism by which ligands affect the drying properties of tung oil.

μ-1,6-Dioxo-1,6-di-phenyl-hexane-3,4-diolato-bis-[(2,2'-bi-pyridine)-chlorido-copper(II)] dihydrate.

The reaction of CuCl2 with 1,6-diphenyl-1,3,5,6-hexa-netetrone and 2,2'-bi-pyridine (bipy) in ethanol gave crystals of the corresponding bimetallic complex, [Cu2(C18H12O4)Cl2(C10H8N2)2]·2H2O. The mol-ecule is centrosymmetric with each CuII ion coordinated to two oxygen atoms from the tetronediate, two nitro-gen atoms from a bipy ligand and one coordinated chloride ion. A water mol-ecule of crystallization forms hydrogen bonds to the chloride ions, linking the mol-ecules into a chain parallel to the bc-face diagonal.

Synthesis, crystal structure and Hirshfeld surface analysis of a copper(II) complex involving 3-methyl-benzoate and 2,2'-bi-pyridine ligands.

3-Methyl-benzoic acid (3-mbH) and 2,2'-bi-pyridine (bipy) reacted with a cop-per(II) salt forming a new mixed ligand complex, aqua-(2,2'-bi-pyridine-κ2 N,N')bis-(3-methyl-benzoato)-κ2 O,O';κO-copper(II) 0.68-hydrate, [Cu(C8H7O2)2(C10H8N2)(H2O)]·0.68H2O or [Cu(3-mb)2(bipy)(H2O)]·0.68H2O. The coord-ination environment of CuII is a distorted octa-hedron. The metal atom is attached to two 3-mb moieties, which bind in monodentate and bidentate fashions. One of the 3-mb units is disordered. The coordination environment is completed by one bipy ligand and a water mol-ecule. A second water mol-ecule is outside the coordination sphere of the CuII atom and its occupancy refined to 0.68. The structure consists of chains along the b-axis direction formed by complex units joined via hydrogen bonds between the coordinated water mol-ecule and an O atom of a coordinated 3-mb unit. Hirshfeld surface analysis indicates that the most abundant contacts are H⋯H (56.8%), H⋯C/C⋯H (21.7%) and H⋯O/O⋯H (13.7%).

The First Cu(I)-Peptoid Complex: Enabling Metal Ion Stability and Selectivity via Backbone Helicity.

Stabilization of Cu(I) is ubiquitous within native copper proteins. Understanding how to stabilize Cu(I) within synthetic biomimetic systems is therefore desired towards biological applications. Peptoids are an important class of peptodomimetics, that can bind metal ions and stabilize them in their high oxidation state. Thus, to date, they were not used for Cu(I) binding. Here we show how the helical peptoid hexamer, having two 2,2'-bipyridine (Bipy) groups that face the same side of the helix, forms the intramolecular air stable Cu(I) complex. Further study of the binding site by rigorous spectroscopic techniques suggests that Cu(I) is tetracoordinated, binding to only three N atoms from the Bipy ligands and to the N-terminus of the peptoid's backbone. A set of control peptoids and experiments indicates that the Cu(I) stability and selectivity are dictated by the intramolecular binding, forced by the helicity of the peptoid, which can be defined as the second coordination sphere of the metal center.

Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor.

This paper describes the synthesis and characterization of seven different copper(II) coordination compounds, as well as the formation of a protonated ligand involving all compounds from the same reaction. Their synthesis required hydrothermal conditions, causing the partial in situ transformation of 5-fluoro uracil-1-acetic acid (5-FUA) into an oxalate ion (ox), as well as the protonation of the 4,4'-bipyridine (bipy) ligand through a catalytic process resulting from the presence of Cu(II) within the reaction. These initial conditions allowed obtaining the new coordination compounds [Cu2(5-FUA)2(ox)(bipy)]n·2n H2O (CP2), [Cu(5-FUA)2(H2O)(bipy)]n·2n H2O (CP3), as well as the ionic pair [(H2bipy)+2 2NO3-] (1). The mother liquor evolved rapidly at room temperature and atmospheric pressure, due to the change in concentration of the initial reagents and the presence of the new chemical species generated in the reaction process, yielding CPs [Cu(5-FUA)2(bipy)]n·3.5n H2O, [Cu3(ox)3(bipy)4]n and [Cu(ox)(bipy)]n. The molecular compound [Cu(5-FUA)2(H2O)4]·4H2O (more thermodynamically stable) ended up in the mother liquor after filtration at longer reaction times at 25 °C and 1 atm., cohabiting in the medium with the other crystalline solids in different proportions. In addition, the evaporation of H2O caused the single-crystal to single-crystal transformation (SCSC) of [Cu(5-FUA)2(H2O)(bipy)]n·2n H2O (CP3) into [Cu(5-FUA)2(bipy)]n·2n H2O (CP4). A theoretical study was performed to analyze the thermodynamic stability of the phases. The observed SCSC transformation also involved a perceptible color change, highlighting this compound as a possible water sensor.

Accessing Lanthanide Metallocene Two-Electron Reduction Chemistry Using 2,2′-Bipyridine

The feasibility of using redox-active 2,2′-bipyridine (bipy) as a synthetically convenient electron carrier to enable lanthanide metallocenes to effect two-electron reduction chemistry has been examined. The Ln(III) precursor complexes, Cp*2LnCl(bipy), 1-Ln (Ln = Nd, Gd; Cp* = C5Me5), were readily synthesized in 75–81% yield in one pot from LnCl3, KCp*, and bipy and were identified by X-ray crystallography. Treatment of the 1-Ln compounds with K/KI (4.3 wt %) afforded in 74–77% yield the products, Cp*2Ln(bipy), 2-Ln, which contain (bipy)1– ligands based on their spectroscopic characteristics and X-ray crystal structures. The molecular structure of the previously reported 2-Eu was also determined, which showed structural features consistent with a neutral bipy ligand. Further reduction of 2-Nd or 2-Gd, or the previously reported 2-Sm, 2-Eu, and 2-Yb with K/KI (4.3 wt %) in the presence of 2.2.2-cryptand (crypt) afforded in 58–88% yield the salts, [K(crypt)][Cp*2Ln(bipy)], 3-Ln, which show metrical parameters identified by X-ray crystallography that are consistent with a (bipy)1– ligand for 3-Eu and 3-Yb and a (bipy)2– ligand for 3-Nd, 3-Sm, and 3-Gd. The two-electron reduction of azobenzene (PhN=NPh) to (PhN−NPh)2– using the 3-Ln complexes was examined as a proof of concept. The 1:1 reactions of 3-Nd, 3-Sm, and 3-Yb with azobenzene afforded in 36–79% yield the [K(crypt)][Cp*2Ln(N2Ph2)], 4-Ln (Ln = Nd, Sm, Yb) complexes, each of which were crystallographically characterized. In another example of two-electron reduction by 3-Ln, treatment of 3-Nd or 3-Sm with elemental sulfur afforded in 70–75% yield [K(crypt)][Cp*2Ln(S5)], 5-Ln (Ln = Nd, Sm), which were shown by crystallography to be rare examples of f-element organometallic complexes that contain the (S5)2– ligand.

Molecular structure of Ru(II)/diphosphine/4,6-dimethyl-2-pyrimidinethiol complexes: A combined experimental and density functional theory study

Reactions of cis-[RuCl2(P-P)(bipy)] precursors with the SpymMe2 ligand (4,6-dimethyl-2-pyrimidinethiol) yielded complexes of the [Ru(SpymMe2)(P-P)(bipy)]PF6 type, where P-P = 1,2-bis(diphenylphosphino)ethane (dppe - for complex 1), 1,3-bis(diphenylphosphino)propane (dppp - for complex 2) and 1,1’-bis(diphenylphosphino)ferrocene (dppf - for complex 3) and bipy = 2,2’-bipyridine. The new compounds were obtained by displacing the chlorido ligands from the precursors and coordination of one monoanionic 4,6-dimethyl-2-pyrimidinethiol ligand. All complexes were characterized by spectroscopic, electrochemical and elemental analysis techniques, as well as single-crystal X-ray diffraction, where the structures of complexes 1, 2 and 3 showed that the SpymMe2 ligand coordinates to the ruthenium(II) center as bidentated, yielding complexes with the sulfur atom trans positioned to the nitrogen atom from the bipy ligand. A theoretical study of the structures of the complexes was performed using the DFT/B3LYP method. Distances and angles of optimized structures agree with X-ray experimental data. Furthermore, the calculated IR and UV-Vis spectra are compatible with experimental data. Charge decomposition analysis (CDA) and NBO (natural bond orbitals) charges showed that there was an overall charge transfer from bipy and P-P ligands to the ruthenium centers. Higher electrochemical stability and 1H and 31P{1H} NMR shifts of 1, 2 and 3 compared with precursors could be explained by the lower values of calculated molecular orbital energies, NBO charge on atoms and CDA data. Finally, the structure of the isomers of complexes 1, 2 and 3, considering the sulfur atom trans positioned to the phosphorus atom, were optimized, showing that they are slightly less stable, presenting total energy higher, 10.4, 31.5 and 60.5 kJ/mol than 1, 2 and 3, where nitrogen is trans to the phosphorus atom.

A new copper(II) complex containing triclopyr: one-pot crystallization, structure, conformation and Hirshfeld surface analyses

Abstract A new copper(II) complex [Cu(3,5,6-tcpa)(2,2′-bipy)Cl] (1) has been obtained through the one-pot hydrothermal reaction of copper chloride dihydrate with triclopyr (systematic name 2-((3,5,6-trichloropyridin-2-yl)oxy)acetic acid, abbreviation 3,5,6-Htcpa) and 2,2′-bipyridine (2,2′-bipy) coligands. 1 has crystallized in triclinic crystal system, P 1 ‾ $\overline{1}$ space group. The central copper(II) ion displayed a distorted square–pyramidal geometry and was connected by one chlorido co-ligand (Clˉ), one 3,5,6-tcpa anionic chelator and one chelating 2,2’-bipy ligand to afford a mononuclear structure. 1 is further extended into a 3D network by the non-covalent interactions of H⋯Cl, H⋯O hydrogen bonds, aromatic π⋯π stacking together with Cl⋯Cl halogen bond interactions. The co-crystallization process, the crystal structure of 1 as well as the Hirshfeld surface analysis for 1 have been analyzed and described. In addition, the flexible conformation of phenoxy methylene group among 1, triclopyr acid and its previously reported co-crystallized compound also have been carefully compared and discussed.

Highly sensitive fluorescent sensing and photocatalytic degradation performance of two-dimensional Tb-organic network

A novel tetra-nuclear Tb-organic network, named as [Tb4(2-pyia)6(HAc)0.5(2,2′-bipy) (H2O)4.5]·2,2′-bipy·H2O (1), was synthesized hydrothermally based on 5-(pyridin-2-ylmethoxy) isophthalic acid (H2pyia) and 2,2′-bipyridine (2,2′-bipy) ligands, and characterized by single crystal X-ray diffraction, thermogravimetric (TG) analyses, powder X-ray diffraction (PXRD) and infrared (IR) technology. 1 possesses a two-dimensional network based on the tetra-nuclear inorganic building units, and the π-π stacking interactions between the pyia2− ligands and the guest 2,2′-bipy molecules play an important role in the forming of 3D supramolecular structure. 1 exhibits excellent fluorescent sensing performance for Fe3+ (1.26 × 10−8 mol/L), Cr2O72− (8.1 × 10−7 mol/L), 2,4,6-trinitrophenol (TNP) (2.71 × 10−8 mol/L) and tetracycline (TCT) (2.76 × 10−7 mol/L) in aqueous solution with lower detection concentrations. The sensing mechanisms of 1 were investigated by density functional theory (DFT) calculations, ultraviolet–visible (UV-Vis) diffuse reflectance spectroscopy, PXRD and fluorescent lifetime analyses. The activated product of 1 was prepared by heating at 255 °C under constant pressure and used to photo-catalytically degrade TCT. Both 1 and the activated one have good photocatalytic degradation performance for TCT with degradation rates of 84.29% and 96.07%, respectively. The photocatalytic mechanisms were discovered by UV–Vis diffuse reflectance spectroscopy and radical trap experiments. The Tb-organic framework might be an excellent multifunctional fluorescent sensor and a good photocatalytic agent for TCT degradation in the future.

A 2D layered Cd(II) coordination polymer supported by in situ generated tetracarboxylate ligand: luminescence sensing for Co2+ ions

AbstractA new Cd(II) coordination polymer of [Cd(H2L)(4,4’‐bipy)(H2O)]n (1, H4L=4‐[(3,4‐dicarboxyphenyl)disulfanyl]benzene‐1,2‐dicarboxylic acid, 4,4’‐bipy=4,4’‐bipyridine) was hydrothermally synthesized. The H4L ligand was in situ generated via the formation of disulfide bond between two 4‐sulfanylbenzene‐1,2‐dicarboxylic acid molecular. The in situ generated H4L ligand deprotonated two protons into H2L2−, which acts as a bidentate ligand to connected Cd(II) ions into a 2D layered structure with the assistance of 4,4’‐bipy ligands. The solids of 1 emits strong blue luminescence, and can be used as a luminescence probe for the detection of Co2+ ions. The limit of detection (LOD) of Co(II) ions by 1 was calculated to be 5.4 μM.