Amanpreet Kaur Jassal

Organocatalytic enantioselective aza-Henry reaction of ketimines derived from isatins: access to optically active 3-amino-2-oxindoles

An organocatalytic asymmetric aza-Henry reaction of ketimines derived from isatins with nitroalkanes has been achieved using Cinchona alkaloid organocatalysts. This method works efficiently with several ketimines to produce a good (up to 82%) yield of the corresponding 3-substituted 3-amino-2-oxindoles with a good (up to 89%) enantiomeric excess.

Neodymium 1D systems: targeting new sources for field-induced slow magnetization relaxation

Two non-isostructural homometallic 1D neodymium species displaying field-induced slow magnetization relaxations are presented together with theoretical studies. It is established that both systems are better described as organized 1D single molecule magnets (SMMs). Studies show great potential of Nd(III) ions to provide homometallic chains with slow magnetic relaxation.

Synthesis, crystal structure determination of two-dimensional supramolecular co-ordination polymer of silver(I) with 1,2-Bis(phenylthio)ethane and its Hirshfeld surface analysis

AbstractThe 2-D polymeric complex (I) has the formula [Ag(phSE)(NO3)]n, which has been crystallized from methanol-acetonitrile mixture and characterized by elemental analysis and single-crystal X-ray diffraction analysis. In this polymer, each Ag(I) ion occupies distorted trigonal pyramidal geometry coordinating with two sulphur atoms from two different ligands and two oxygen atoms from two NO3 groups. Each NO3 acts as a bridging ligand coordinating through its two oxygen atoms to different Ag(I) ions. The Ag(I) ion and NO3 group are in plane with torsion angle 176.43∘. All the ligands adopt anti-conformation but the relative orientation of two -S-C-C-S units is perpendicular to one another such that two phenyl rings attached to the two sulphur atoms coordinating to a particular Ag ion lie on the same side. Each NO3 bridges two neighbouring Ag ions belonging to two different -S-Ag-S-C-C-S-Ag-S- tapes running along a-axis where two phenyl rings are not parallel to each other to reduce the steric hindrance and maximize packing. The adjacent chains are fused to form 2D sheet by bridging both through bidentate phSE ligand and NO3 anion stacking in ab plane. The structure consists of 4-c uninodal net where Point symbol for Ag (I) ion and net is (44.62) with sql type topology. X-ray diffraction analysis and Hirshfeld surface analysis give rise to comparable results but in Hirshfeld surface analysis, two-third times more close contacts are obtained. The fingerprint plots demonstrate that these weak non-bonding interactions are important for stabilizing the crystal packing. Graphical AbstractIn this 2-D polymeric complex, Ag(I) ion occupies distorted trigonal pyramidal geometry. Ag(I) is coordinating with two sulphur atoms from two different ligands and two oxygen atoms from two NO3 groups. Each NO3 acts as a bridging ligand coordinating through its two oxygen atoms to different Ag(I) ions. All the ligands adopt anti-conformation and phenyl rings are placed in such a way to generate π-π interactions. The structure consists of 4-c uninodal net where point symbol for Ag (I) ion and net is (44.62) with sql type topology.

Synthesis and structures of 5-nitro-salicylaldehyde thiosemicarb-azonates of copper(II): molecular spectroscopy, ESI-mass studies, antimicrobial activity and cytotoxicity

The basic objective of this investigation is to explore potential metallo-organic antimicrobial agents based on metal–thiosemicarbazonates. This study acquires significance in the light of the antibacterial resistance exhibited by Gram-positive and Gram-negative bacteria which have become a serious global medical problem. The increasing drug resistant bacteria are responsible for various nosocomial infections and among these, methicillin resistant Staphylococcus aureus (MRSA) is the most frequent nosocomial pathogen. Likewise, Candida albicans (fungi) are found to have developed resistance against a number of antifungal agents. In this context, compounds of copper(II) with salicylaldehyde based thiosemicarbazones {5-R′-2-HO–C6H4–C2(H)N3–N2H–C1(S)–N1HR; R = H, Me, Et, Ph: H2L1, H2L2, H2L3, H2L4 respective thio-ligands] using bipyridines/phenanthrolines (L′) as co-ligands are being tested against various microorganisms (bacteria/fungi). For R′ = methoxy, several complexes (five coordinate complexes) were tested recently against Gram positive bacteria such as Staphylococcus aureus (MTCC740), methicillin resistant Staphylococcus aureus (MRSA), Gram negative bacteria, Shigella flexneri (MTCC1457), Klebsiella pneumoniae (MTCC109), P. aeruginosa (MTCC741) and yeast, Candida albicans (MTCC227). These complexes displayed significant growth inhibitory action even with low MIC (minimum inhibitory concenteration). A series of new copper(II) complexes (R′ = nitro, keeping R and co-ligands same) namely, [Cu(κ3-O,N,S–L)(κ2-N,N-L′)] {(L)2− = (L1)2−, L′ = bipy, 1, phen, 2; (L)2− = (L2)2−, L′ = bipy, 3, phen, 4; (L)2− = (L3)2−, L′ = bipy, 5, phen, 6; (L)2− = (L4)2−, L′ = bipy, 7, phen, 8} have been isolated and characterized by elemental analysis, infrared and electronic absorption spectroscopy, ESR spectroscopy, fluorescence, and single crystal X-ray crystallography. These copper(II) complexes have been investigated for their antimicrobial activity (antibacterial and antifungal activity), viable cell count studies through time kill assays and cellular toxicity testing using MTT assays against the above mentioned bacteria/fungi. Several complexes have shown bactericidal effects with low cytotoxicity towards living cells (sheep blood used).

Synthesis, structure, computational, antimicrobial and in vitro anticancer studies of copper(II) complexes with N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine and tris(2-hydroxyethyl)amine

The present work consists of synthesis, structural characterization, spectral, density functional theory (DFT), antimicrobial, and anticancer studies of two copper(II) complexes, [Cu(THEEN)(DNB)](DNB) (1) and [Cu(TEAH3)2](DNB)2 (2). In these complexes, THEEN is N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, a tetrapodal ligand, and TEAH3 is tris(2-hydroxyethyl)amine, a tripodal ligand, and the counter-anion is 3,5-dinitrobenzoate (DNB−). X-ray crystallography studies reveal that both complexes have distorted octahedron geometries. DFT studies have been performed to calculate structural parameters, vibrational bands, and energy gaps of frontier orbital (HOMO-LUMO) with B3LYP/6–31G*/LANL2DZ level of theory using DMSO as solvent. The theoretical and crystallographic analyses are consistent. Antimicrobial studies have been performed with new copper(II) complexes against Gram(+) bacteria (Staphylococcus aureus), Gram(−) bacteria (Serratia marcescens, Sphingobium japonicum, and Stenotrophomonas maltophilia) and fungal species (Candida albicans, Aspergillus niger, and Saccharomyces cerevisiae). The copper(II) complexes have also shown in vitro cytotoxicity on MCF-7, HCT-116, and HL-60 human cell lines. This study demonstrates that 2 was active against MCF-7 cell lines with IC50 of 23 μg/mL. The present work consists of synthesis, crystal structure, DFT studies, antimicrobial, and anticancer activities of [Cu(THEEN)(DNB)](DNB) (1) and [Cu(TEAH3)2](DNB)2 (2). Both complexes have distorted octahedron geometries with Jahn–Teller distortion. The theoretical and crystallographic analyses are consistent with each other.

Synthesis, molecular structures and ESI-mass studies of copper(I) complexes with ligands incorporating N, S and P donor atoms

AbstractEquimolar reaction of copper(I) bromide with 2-thiouracil (tucH2) in acetonitrile-methanol formed a light yellow solid which on subsequent treatment with a mole of triphenyl phosphine (PPh3) in chloroform has yielded a sulfur-bridged dinuclear complex, [Cu2Br2(μ-S-tucH2)2(PPh3)2] ⋅2CHCl31. A reaction of copper(I) bromide with two moles of 2,4-dithiouracil (dtucH2) in acetonitrile-methanol followed by addition of two moles of PPh3, designed to form [Cu(μ-S,S-dtuc)2(PPh3)4Cu] 2a, instead resulted in the formation of previously reported polymer, {CuBr(μ-S,S-dtucH2)(PPh3)}n2. Reaction of copper(I) iodide with 2-thiouracil (tucH2) and PPh3 in 1:1:2 molar ratio (Cu:H2tuc:PPh3) as well as that of copper(I) thiocyanate with pyridine-2-thione (pySH) or pyrimidine-2-thione (pymSH) and PPh3 in similar ratio, yielded an iodo-bridged unsymmetrical dimer, [(PPh3)2(μ-I)2Cu(PPh3)] 3 and thiocyanate bridged symmetrical dimer, [(PPh3)2Cu(μ-N,S- SCN)2Cu(PPh3)2] 4, respectively. In both the latter reactions, thio-ligands which initially bind to Cu metal center, are de-ligated by PPh3 ligand. Crystal data: 1, P21/c: 173(2) K, monoclinic, a, 13.4900(6); b, 17.1639(5); c, 12.1860(5) Å; β, 111.807(5) ∘; R, 5.10%; 2, Pbca: 296(2) K, orthorhombic, a, 10.859(3); b, 17.718(4); c, 23.713(6) Å; α=β=γ, 90 ∘; R, 4.60%; 3, P21: 173(2) K, monoclinic, a, 10.4208(7); b, 20.6402(12); c, 11.7260(7) Å; β, 105.601(7)∘; R, 3.97%; 4, P-1: 173(2) K, triclinic, a, 10.2035(4); b, 13.0192(5); c, 13.3586(6) Å; α, 114.856(4); β, 92.872(4)∘; γ, 100.720(4)∘; R, 3.71%. ESI-mass studies reveal different fragments of complexes. Graphical AbstractSulfur-bridged dimer [Cu2Br2(μ-S-tucH2)2(PPh3)2]·2CHCl31 is the first example of a dinuclear complex of 2-thiouracil/ 2,4-dithiouracil class of ligands.

Reactivity of thiazolidine-2-thione towards CuI/CuII: Synthesis and structures of [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide and [bis(2,2′-bipyridine)nitratocopper(II)] nitrate

AbstractThiazolidine-2-thione (L1, NC3H5S2) reacted with copper(I) bromide in CH3CN under aerobic conditions and transformed through C–S bond cleavage into 3-(2-thiazolin-2-yl)thiazolidine-2-thione (L2, C3H4S2N-C3H4SN). This thio-ligand L2 with CuI ion yielded a three coordinate complex, [3-(2-Thiazolin-2-yl)thiazolidine-2-thione]copper(I)bromide 1a which crystallized in the triclinic system with the space group P1 as reported earlier. Treatment of 1a with bis(diphenylphosphino)methane (dppm) in dichloromethane also formed [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide 1b but it crystallized into the triclinic system with a new space group, P-1: 296(2) K, a, 7.3890(19); b, 8.473(2); c, 9.491(2) Å; α, 70.273(5); β, 67.170(5); γ, 84.949(5)∘; R, 6.79%. Reactions of copper(II) nitrate with thiazolidine-2-thione followed by the addition of 2,2′-bipyridine or with 2,2′-bipyridine first followed by the addition of thiazolidine-2-thione, gave blue crystals in both the cases. The x-ray crystallography revealed stoichiometry of the complex formed as: [Cu(κ2-N,N′-bipy)2(κ1-ONO2)](NO3)2, which crystallized in monoclinic crystal system with space group, P21/n(14). Crystal data: 173(2) K, a, 11.318(1), b, 12.160(1), c, 14.967(1) Å; β = 98.01(1)∘, R, 3.99%; 296(2) K, a, 11.340(5), b, 12.249(5), c, 15.065(6) Å; β = 98.04(2)∘, R, 4.09%. Graphical AbstractThiazolidine-2-thione with copper(I) bromide in CH3CN under aerobic conditions yielded red brown crystals which on treatment with bis(diphenylphosphino)methane in dichloromethane formed [3-(2-thiazolin-2-yl)thiazolidine-2-thione]copper(I) bromide which crystallized into triclinic system with space group, P-1.

Supramolecular architectures of N,N,N′,N′-tetrakis-(2-hydroxyethyl)ethylenediamine and tris(2-hydroxyethyl)amine with La(III) picrate

The present work consists of synthesis, crystal structure and computational analyses of supramolecular architectures: complexes [La(THEEN)(PIC)(H2O)2](PIC)2·2H2O (1), [La(TEAH3)2(H2O)2](PIC)3 (2) and compounds [THEENH2+ (PIC−)2] (I) and [TEAH4+( PIC−)] (II) where THEEN is N,N,N′,N′-tetrakis-(2-hydroxyethyl)ethylenediamine (a tetrapodal ligand) and TEAH3 is triethanolamine (a tripodal ligand). Compounds I and II are formed as a result of the proton-transfer from picric acid to the tetrapodand and tripodand respectively. The chains of tetrapodal ligand (THEEN) coordinate through all their six potential donor sites to the La(III) ion. The torsion angle of the N–C–C–N moiety is anti in compound (I) while it is gauche in compound 1. The chains of the tripodal ligand (TEAH3) coordinate to La(III) through all their four potential donor sites. The complexes (1) and (2) have acquired distorted bicapped square-antiprismatic geometry with a coordination number 10. Computational studies of complexes 1 and 2 and compounds I and II in the gaseous state revealed a good coherence of structural parameters with that of crystal structure analyses. B3LYP/6-31G level of Gaussian 03 has been used for optimization, calculation of structural parameters and energy gaps of frontier orbitals (HOMO–LUMO) for complexes 1, 2 and compounds I and II. The additional LANL2DZ set was used to locate La(III) for performing calculations in complexes 1 and 2. Theoretically computed HOMO–LUMO studies predicted that both complexes and compounds are stable. The reported work is discussed from four aspects: supramolecular architectures, lanthanum coordination chemistry, torsion angles of the ligands in the proton-transfer species I and II with the complexes 1 and 2 and comparison of their crystal structures with the computationally optimized structures of all the four species i.e., complexes 1, 2 and supramolecular architectures I and II.

Synthesis and structural characterization of donor-stabilized disubstituted diphenyldithiophosphates of nickel(II)

Donor-stabilized addition complexes of nickel(II) with disubstituted diphenyldithiophosphates, [{(ArO)2PS2}2NiL2] {Ar = 2,4-(CH3)2C6H3 [(1), (5)], 2,5-(CH3)2C6H3 [(2), (6)], 3,4-(CH3)2C6H3 [(3), (7)] and 3,5-(CH3)2C6H3 [(4), (8)]; L = C5H5N [(1)-(4)] and C7H9N [(5)-(8)]}, were successfully isolated and characterized by elemental analysis, magnetic moment, IR spectroscopy and single-crystal X-ray analysis. Compound (4) crystallizes in the monoclinic space group P2(1)/n whereas compounds (7) and (8) crystallize in the triclinic space group P1. The single-crystal X-ray diffraction analysis of (4), (7) and (8) reveals a six-coordinated octahedral geometry for the NiS4N2 chromophore. Two diphenyldithiophosphate ions act as bidentate ligands with their S atoms coordinated to the Ni centre. Each of them forms a four-membered chelate ring in the equatorial plane. The N atoms from two donor ligands are axially coordinated to the Ni atom.

CCDC 1500393: Experimental Crystal Structure Determination

Related Article: Amanpreet Kaur Jassal, Love Karan Rana, Geeta Hundal|2017|CrystEngComm|19|2021|doi:10.1039/C6CE02640K