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[Rh(α-NaiR)2Cl2]ClO4 (2) (α-NaiR (1), 1-alkyl-2-(naphthyl-α-azo)imidazoles, R = Me (a), Et (b)) complexes react with ArNH2 (where Ar = X C6H4 , X = H (3), Me (4), Cl (5)) to synthesize the naphthyl appended C N fused bis-[1-alkyl-2-{(7-imidoaryl)naphthyl-α-azo}imidazole-N,N′,N″]rhodium(III)perchlorate complexes [Rh(α-NaiR N Ar)2]ClO4 (3–5). The single crystal X-ray diffraction measurements of one of the complexes, [Rh(α-NaiEt N C6H5)2]ClO4 (3b), confirms the structure. The absorption spectra of the complexes 3–5 show high intense broad multiple transitions at 650–800 nm compared to the transition of the precursor 2 at 500 nm and DFT computations have assigned this transition to an admixture of LLCT (ligand-to-ligand charge transfer, imidoaryl → azonaphthyl) and LMCT transitions. The cyclic voltammogram shows a quasireversible oxidation at >0.8 V, which is assigned by DFT computation to oxidation of the imidoaryl chelate, along with azo reductions at

Two discrete manganese(III) coordination compounds, [Mn(L)(OCN)]2 (1) and [Mn(L′)(H2O)2][dnba]·DMF·H2O (2) bearing in situ generated Schiff base ligands H2L [H2L = N,N′-o-phenylenebis(salicylaldimine)] or H2L′ [H2L′ = N,N′-bis(salicylidene)ethylenediamine], were easily prepared by treating Mn(CH3COO)2·4H2O with salicylaldehyde and o-phenylenediamine (for 1) or ethylenediamine (for 2), and in the presence of supporting cyanate ligands or 3,5-dinitrobenzoate (dnba) counter anions, respectively. The obtained products were isolated as air-stable crystalline solids and were fully characterized by spectroscopic methods, single-crystal X-ray diffraction, topological analysis, as well as theoretical methods. The X-ray diffraction of the compound 1 reveals that the structure is dimeric with phenolic oxygen atom acting as bridge between two symmetrically equivalent Mn(III) atoms. The structure of 2 contains mononuclear cationic [Mn(L′)(H2O)2] units along with a 3,5-dinitrobenzoate anion and crystallization DMF molecule. Structural analysis indicates a distorted octahedral geometry for both complexes. Intermolecular hydrogen bonding and π–π stacking interactions are present in the lattice and play an important role in cohesion of the structures. Topological analysis of the compound 2 reveals a binodal 3,4-connected underlying 2D net with the 3,4L13 topology. Noncovalent interactions were investigated in terms of energies and geometries using theoretical calculations. Fluorescence and antibacterial properties of 1 and 2 were also investigated and discussed.

Co-crystallization experiments conducted between ortho-phenylenediamine (OPDA) and five substituted aromatic acids (phthalic acid, salicylic acid, 4-hydroxybenzoic acid, 4-nitrobenzoic acid and 3,5-dinitrobenzoic acid) reveal the formation of supramolecular networks constructed from acid–base heterosynthons of ortho-phenylenediammonium cations with respective aromatic anions. All of these coformers are generally regarded as safe (GRAS) molecules. The five reported crystal structures are sustained predominantly by intermolecular N+−H...O−, N—H...O− and N—H...O hydrogen-bonding interactions; in addition intramolecular O—H...O and intermolecular O—H...O, O—H...O− and C—H...O interactions contribute to the formation of various networks. Five 1:1 salts [NH2C6H4NH3]+·[COOHC6H4COO]− (1); [NH2C6H4NH3]+·[OHC6H4COO]− (2); [{NH2C6H4NH2}2·{OHC6H4COOH}2·{NH2C6H4NH3}+ 2·{OHC6H4COO}− 2] (OPDPHB) (3); [NH2C6H4NH3]+·[NO2C6H4COO]− (4) and [NH2C6H4NH3]+·[(NO2)2C6H4COO]− (5) were isolated as single crystals by the slow evaporation method and were characterized using spectroscopic and X-ray crystallographic techniques. X-ray diffraction studies confirmed the formation of salts. The pK a difference between the amine and respective acid favours the transfer of a proton from the acid to the amine, which leads to the formation of the anion and the cation. The interactions between these ions resulted in a stable heterosynthon in each case. The asymmetric units of salts (1), (2), (4) and (5) contain one anion and one cation each, but salt (3) consists of two anions, two cations and two neutral species in its asymmetric unit. A polymorph of salt (3) was also isolated from the crystallization of the ground material from liquid-assisted grinding [{NH2C6H4NH2}·{NH2C6H4NH3}+·{OHC6H4COO}−] (OPDPHB 3P). The polymorph crystallized in the monoclinic non-centrosymmetric space group P21. The liquid-assisted grinding experiments using a 1:1 ratio also revealed the formation of the expected salts, except salt (3), where this product matches with polymorph (OPDPHB 3P).

The asymmetric unit of the title mol­ecular salt, consists of half a 4-amino­benzenaminium cation and a half a 5-carb­oxy­penta­noate anion. Each ion lies about an inversion centre, the other half being generated by inversion symmetry. In the crystal, charge-assisted O—H⋯O, N—H⋯O and N—H⋯N hydrogen bonds together lead to the formation of a three-dimensional supra­molecular framework., The asymmetric unit of the title mol­ecular salt (systematic name: 4-amino­anilinium 5-carb­oxy­penta­noate), C6H9N2 +·C6H9O4 −, consists of half a 4-amino­benzenaminium cation (4-ABA) and half a 5-carb­oxy­penta­noate anion (5-CP); the other half of each ion is generated by inversion symmetry. Protonation of p-phenyl­enedi­amine (PPDA) leads to the formation of a 1:1 salt, but scrutiny of the crystal structure reveals that both of the amine groups of PPDA are partially protonated, with a half-occupied H atom. For the 5-CP anion, an H atom is positioned on an inversion center midway between two O atoms of inversion-related 5-CP ions. In the crystal, the 5-CP anions are linked by the O—H⋯O hydrogen bond to form chains propagating along the [1-10] direction. The chains are linked via N—H⋯O and N—H⋯N hydrogen bonds involving the 4-ABA cations, forming a three-dimensional supra­molecular framework. The title salt was also prepared by mechanochemical synthesis using liquid-assisted grinding (LAG). Its PXRD pattern matches that of the simulated pattern of the crystal structure of the title mol­ecular salt.

Six new salts of an API intermediate 2-aminothiazole with different carboxylic acid coformers were synthesized and characterized by IR (Infrared spectroscopy), 1H-NMR, DSC (Differential scanning calorimetry), XRPD (X-ray powder diffraction) and single crystal XRD. The crystal structure of the salts with benzoic acid, 2,3-, 2,4-, 2,5-, 2,6- dihydroxybenzoic acids and 2,4-dinitrobenzoic acid were determined. The thiazole moiety exhibited solvent (polarity) assisted tautomerism in all reported salts and proton transfer was noticed to the ring N of thiazole due to which two point supramolecular synthon N+−H(thiazole)⋯O−(acid), N−H(amine)⋯O−(acid) was observed. The crystal structures were studied with respect to the positional effect of the competing functional groups like hydroxyl (−OH) and nitro (−NO2) as well as their donor and acceptor abilities for hydrogen bonding. The presence of the non-conventional hydrogen bond (C−H⋯O) has been found to play a critical role in the formation of secondary supramolecular architectures.

In view of the importance of picolinic acid (PA) in preventing cell growth and arresting cell cycle, new PA based metallonucleases were designed with a view to study their DNA binding and cleavage abilities. Three new Cu(II) complexes [Cu(II)(DPPA)].4H2O (1),[Cu(II)(DPPA)(bpy)].5H2O (2) and [Cu(II)(DPPA)(phen)].5H2O (3), were synthesized using a picolinic acid based bifunctional ligand (DPPA) and heterocyclic bases (where DPPA: Pyridine-2-carboxylic acid {2-phenyl-1-[(pyridin-2-ylmethyl)-carbonyl]-ethyl}-amide; bpy: 2, 2′-bipyridine and phen: 1, 10-phenanthroline). DPPA was obtained by coupling 2-picolinic acid and 2-picolyl amine with l -phenylalanine through amide bond‌‌. Complexes were structurally characterized by a single crystal X-ray crystallography. The molecular structure of 1 shows Cu(II) center essentially in a square planar coordination geometry, while complex 2 shows an approximate five coordinated square-pyramidal geometry. Eventhough we could not isolate single crystal for complex (3), its structure was established based on other techniques. The complex (3) also exhibits five coordinate square pyramidal geometry. The complexes show good binding affinity towards CT-DNA. The binding constants (Kb) decrease in the order 1.35 ± 0.01 × 105 (3) > 1.23 ± 0.01 × 105 (2) > 8.3 ± 0.01 × 104 (1) M−1. They also exhibit efficient nuclease activity towards supercoiled pUC19 DNA both in the absence and presence of external agent (H2O2). The kinetic studies reveal that the hydrolytic cleavage reactions follow the pseudo first-order rate constant and the hydrolysis rates are in the range of (5.8–8.0) × 107 fold rate enhancement compared to non-catalyzed double stranded DNA (3.6 × 10−8 h−1).

The three-components reaction of dimethyltin dibromide with imidazo[1,2-a]pyridine and allyl bromide in ethanol affords an ionic complex, bis(1-allylimidazo[1,2-a]pyridinium) dimethyltetrabromostannate(II). X-ray crystal structure analysis of the complex reveals the tin atom to be hexacoordinated, forming a dianion. Organotin(IV) halides on reacting with imidazo[1,2-a]pyridines yield 1:2 complexes. The X-ray crystal structure analysis of such a complex shows the tin atom to be hexacoordinated, with two imidazo[1,2-a]pyridine molecules coordinated through the N1 atom. Bis(imidazo[1,2-a]pyridine)dimethyltin dibromide does not show any reactivity towards allyl bromide or 1-(1-pyrrodinyl)cyclohexene, even on refluxing in ethanol.

A novel 2-Amino-6-nitrobenzothiazole (2A6NBT) complex of tetrathiafulvalene (TTF) was synthesized and crystal structure of (TTF)-(2A6NBT) 2 is reported. The asymmetric unit is found to have half molecule of TTF and one molecule of 2-Amino-6-nitrobenzothiazole. Several short interactions of type π–π, nonconventional Van der Waals and hydrogen bonding were observed in this complex. Localization of the inversion center lead to the presence of 2A6NBT moieties in the trans position. Van der Waals type short interactions existed predominantly between one TTF and six 2A6NBT molecules. The C–C bond length of 1.314 A in (TTF)-(2A6NBT) 2 is the shortest C–C bond distance reported among the TTF molecules studied so far. TTF's and 2A6NBT molecules are nearly orthogonal to each other. TTF form segregated stacks along the c axis and exhibit a novel “stair case” structure. The extensive short interactions lead to supramolecular architectures. Two probe room temperature conductivity value of powder was (∼1.4×10 −7 S/cm) found to be within the semiconducting range measurements. Density functional calculations using the hybrid functional B3LYP with 6–31 G (d) basis set indicated thermodynamically favored product. Scanning electron microscopy images revealed rod like microstructures.

A novel series of Pd(II) complexes derived from 2-thiophenecarboxaldehyde and 1,8-diaminonaphthalene has been synthesized and characterized by various physico-chemical and spectroscopic techniques viz., elemental analyses, IR, UV–vis, 1 H and 13 C NMR spectroscopy, and ESI-mass spectrometry. The structure of ligand, 2-(2-thienyl)-2,3-dihydro-1H-perimidine has been ascertained on the basis of single crystal X-ray diffraction. All Pd(II) complexes together with the corresponding ligand have been evaluated for their ability to suppress the in vitro growth of microbes, Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa , Citrobacter sp., Bacillus subtilis and Stenotrophomonas acidaminiphila and results show that Pd(II) complexes have more significant antimicrobial activity than their corresponding ligand. Fluorescence spectroscopic measurements clearly support that both of the Pd(II) complexes show significant DNA binding with calf thymus DNA.

A novel copper(I) Schiff base complex has been synthesized and fully characterized by spectral, analytical and structural modes. Single crystal X-ray diffraction studies revealed that the copper(I) complex [CuCl(PPh3)L] has a distorted tetrahedral geometry around the central copper(I) ion. The interaction of the ligand and the complex with CT-DNA has been explored by absorption titration method which revealed that the compounds could interact with CT-DNA through intercalation. A gel electrophoresis assay demonstrated the ability of the complex to cleave the pBR322 DNA. The antioxidative properties showed that the copper(I) complex has a strong radical-scavenging potency than ligands. Further the cytotoxic effect of the compounds examined on cancerous cell lines showed that the complex exhibited substantial anticancer activity.

A family of novel platinum group metal complexes containing bidentate chelating 1-pyrimidyl-3-methylimidazolyl bromide ( HL1 · Br ) and 1-pyrimidyl-3-methylimidazolyl-2-thione ( L2 ) ligands has been synthesized. The synthetic protocol for the formation of these complexes differs from one ligand to the other. Treatment of ligand ( HL1 · Br ) with the metal precursors led to the formation of complexes via in situ carbene transfer reactions. The silver–NHC complex ( 1 ) was formed by the reaction of HL1 · Br with silver oxide under light-free conditions. Subsequent addition of appropriate metal precursors to the silver–NHC complex yielded [(η 6 -arene)Ru( L1 )Cl]PF 6 complexes {arene = C 6 H 6 ( 2 ), p - i PrC 6 H 4 Me ( 3 ), C 6 Me 6 ( 4 )} on stirring at room temperature, whereas the complexes [CpRu( L1 )(PPh 3 )]PF 6 {Cp = C 5 H 5 (5), C 9 H 7 ( 6 )} were obtained under reflux conditions. In the case of ligand L2 , stirring of equimolar quantities of metal precursors and the ligand at room temperature yielded [(η 6 -arene)Ru( L2 )Cl]PF 6 {arene = C 6 H 6 (7), p - i PrC 6 H 4 Me ( 8 ), C 6 Me 6 ( 9 )}, and [Cp ∗ M( L2 )Cl]PF 6 {Cp ∗ = C 5 Me 5 , M = Rh ( 10 ), Ir ( 11 )}. All these complexes were characterized by CHN analysis, IR, NMR and mass spectrometry besides confirmation by single crystal X-ray diffraction studies for some representative complexes as their hexafluorophosphate salts [ 3 ]PF 6 , [ 5 ]PF 6 , [ 8 ]PF 6 and [ 10 ]PF 6 .

Experimental and theoretical studies of a new class of novel annulated imidazolium scffords 2a, 2b, 2c and their Hg(II)–NHC complexes 3a, 3b and 3c have been synthesized and characterized by different spectroscopic techniques. Molecular structures of 3a and 3b have been determined by single crystal X-ray diffraction studies. Virtual linear geometry [Ccarbene–Hg–Ccarbene 176.56(17)°] around Hg of the complex 3b is observed where as in 3a and 3c its deviate a more. DFT calculations provide geometrical parameters in conformity with the experimental values in case of 3a. The molecules prefer syn configuration over the anti due to lower energy supported by theoretical studies. Attention has given paid for theoretical calculations and comparison of 3a and 3c to observe the steric effect of –CH3 group in the scaffords where as in case of 3b the –CH3 group remain innocent.

Two organic–inorganic hybrid compounds [Zn2(µ-4-OBz)4(py)2] · 0.5CH3OH (1) and [Zn(2-Cl-OBz)2(py)2] (2) (OBz = benzoate; 2-Cl-OBz = 2-chlorobenzoate; py = pyridine) have been synthesized from aqueous methanol at room temperature and characterized by analytical, spectroscopic, and single-crystal X-ray diffraction. Compound 1 crystallizes in space group P21/c and exhibits a dinuclear paddle-wheel-like structure with Zn—Zn separation of 2.9602(7) A. Zn–O distances in 1 range from 2.0272(18) to 2.057(2) A and Zn–N distances are 2.043(5) and 2.004(9) A. Each Zn has a square-pyramidal geometry bridged by four carboxylates in the basal plane with the pyridine at the apex. The dinuclear unit also contains 0.5 methanol. Compound 2 crystallizes in space group P 1 and consists of discrete molecules having a distorted tetrahedral environment around zinc; 2-chlorobenzoate and pyridine are monodentate. The observed Zn–O distances in 2 are 2.0255(19) and 2.0377(18) A and Zn–N distances are 1.9535(14) and 1.9587(16) A. W...

A series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones have been synthesized by the multicomponent reaction (MCR) of β-naphthol, aryl aldehydes, and dimedone by using BF3:OEt2 as a catalyst. The derived compounds have been analyzed by IR, NMR (1D and 2D), and mass spectra. The single crystal X-ray structural analysis of 9,9-dimethyl-12-(2-nitrophenyl)-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one evidences the envelope conformation of the cyclohexane ring and the pyran ring tends to adopt flattened-boat conformation.

Reaction of aqueous hydroxylamine with carbon disulfide in acetonitrile or in tetrahydrofuron unprecedentedly results in the formation of ammonium thiocyanate and sulfur.

A highly efficient enantioselective S(N)Ar reaction of chiral acyl bicyclic lactam with substituted-2,4-dinitrobenzenes was developed, affording products containing quarternary stereogenic centers. They are further utilized towards an enantioselective synthesis of spirooxoindoles.