Luminescent rhenium(I) complex of azo ligand based on quinoline: Synthesis, characterization and computational investigations

Reaction of 7-(quinolin-8-yldiazenyl)quinolin-6-ol HL, [where H represents the dissociable proton upon complexation] based on quinoline with [Re(CO)5Cl] in toluene afforded brown colored product of composition [(Re(CO)3L]. The mononuclear Re(I) complex was characterized unequivocally. Molecular structure of the complex fac-[(Re(CO)3L] was confirmed by single-crystal X-ray diffraction. The complex exhibited excellent photoluminescence behavior in solution state. The ground and excited-state geometries and absorption properties of the Re(I), complex was further examined by DFT and TDDFT method

Luminescent rhenium(I) complex of azo ligand based on quinoline: Synthesis, characterization and computational investigations

621-628Reaction of 7-(quinolin-8-yldiazenyl)quinolin-6-ol, HL, (where H represents the dissociable proton upon complexation) based on quinoline with [Re(CO)5Cl] in toluene afforded brown colored product of composition [Re(CO)3L]. The mononuclear Re(I) complex has been characterized unequivocally. Molecular structure of the complex fac-[Re(CO)3L] has been confirmed by single-crystal X-ray diffraction. The complex exhibited excellent photoluminescence behavior in solution state. The ground and excited-state geometries and absorption properties of the Re(I), complex has been further examined by DFT and TDDFT methods

Synthesis, structure and characterization of fac-[Re(CO)3]+[Re(CO)_3]^+ complexes derived from hydrazone Schiff bases: DFT– DDFT investigation on electronic structures

The syntheses, structural and spectroscopic characterization of the complexes of general formula $[ReL(CO)_3Cl]$ bearing bifunctional hydrazone Schiff base ligand L are presented in this paper. The structure of one of the complexes is determined by X-ray crystallography. The solid-state structure of the compound is involved in a secondary interaction in lattice forming a supramolecular array. The gas phase geometry optimization and electronic calculation have been performed using density functional theory without any symmetry constraints. On the basis of structural and theoretical studies, ligand in the complexes is considered to be in the keto, not in enol form. Experimental ground state IR and NMR data set agree with those calculated by DFT calculations. The electronic spectra of the complexes are calculated by time dependent density functional theory (TDDFT) using conductor like polarizable continuum model (CPCM). The computed vertical excitation energies in solution are in good agreement with experimental one showing that the metal-to-ligand charge transfer transitions in visible region dominate over ligand based ILCT transition. The TDDFT excited states calculation of the electronic spectra in solution provides evidence towards luminescence spectra

Rhenium(I) complex with 2-(benzothiazol-2-yl) quinoline: Synthesis, characterization, spectral properties and DFT/TDDFT investigations

913-924The red colored mononuclear rhenium(I) complex having fac-[Re(CO)3]+ moiety of general formula, [Re(CO)3(NN)Cl], has been synthesized in excellent yield by reacting [Re(CO)5Cl] with 2-(benzothiazol-2-yl) quinoline (1:1) in a boiling mixture of methanol+chloroform (3:1, v/v) under argon atmosphere. Elemental, 1H and 13C NMR analysis show the formation of the desired complex. The complex is also characterized by different spectroscopic techniques. The ground and excited-state geometries, NMR, absorption, and phosphorescence properties of the Re(I) complex are examined by DFT and TDDFT methods. The natural transition orbital and spin density difference map analysis reveals the nature of excitations. The lowest lying triplet excited state is associated with the 3MLCT/3ILCT excited state. The emission-like transition is consistent with the strong 3MLCT/ 3ILCT character

A benzimidazole-based chemodosimeter for the fluorometric detection of Zn and Cu via 1,5 proton shifts and C–N bond cleavage

Here, we report the design and synthesis of the fluorescent probe APBHN, which was derived from 2- (1H-benzo[d]imidazol-2-yl)benzenamine and is capable of detecting intracellular Zn and Cu ions in the micromolar range. Single-crystal X-ray analysis revealed that the structure of the ligand comprises a fused cyclic system with a pendent naphthol moiety. With the addition of Zn and Cu ions the inherent fluorescence behaviour of the ligand APBHN is perturbed via a chemodosimetric change that involves a 1,5 proton shift followed by C–N bond cleavage. Upon detailed analysis, it was found that the ligand forms 1 : 1 and 1 : 2 (metal to ligand) complexes with the corresponding metal ions. The detection limits of Zn2+ and Cu2+ were 5.59 μM and 0.148 μM, respectively, with APBHN, which are lower than the WHO guidelines (76 μM for Zn2+ and 31.5 μM for Cu2+) for drinking water. Moreover, APBHN could be used as a practical, visible colorimetric test kit for both Zn2+ and Cu2+. APBHN can efficiently detect Zn2+ and Cu2+ in liver carcinoma cells with insignificant cytotoxicit

Sugar vanadates: Synthesis and characterization of a mannopyranoside ester <span style="font-size:14.0pt;font-family:"Times New Roman";mso-fareast-font-family: "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:AR-SA">incorporating VO³^{<span style="font-size:14.0pt;font-family:Arial;mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">+</span>}</span>

405-406The reaction of methyl -4,6-dimethoxy- -D-mannopyranoside (H2man) with [VIVO(L)(H2O)] (L2-, deprotonated salicylaldimine of glycine) in air has afforded [VvO(Hman)(L)] in which the sugar ligand is chelated to the metal via alkoxidic and alcoholic oxygen atoms, the V-O lengths being 1.799(7) Å and 2.366(8) Å respectively.</span

A family of (N-Salicylidene-α-amino acidato)vanadate esters incorporating chelated propane-1,3-diol and glycerol: synthesis, structure, and reaction

The brown colored title complexes, VVO(Asal)(Hpd) and VVO(Asal)(H2pt), have been synthesized in excellent yields by reacting VIVO(Asal)(H2O) with propane-1,3-diol (H2pd) and glycerol (H3pt), respectively, in methanol. Here Asal2- is the deprotonated salicylaldimine of glycine (A = g), L-alanine (A = a), L-valine (A = v), or L-phenylalanine (A = p). The complexes have relatively low oxovanadium(V)-oxovanadium(IV) reduction potentials (-0.2 V vs SCE in dimethyl sulfoxide). The X-ray structures of VO(gsal)(Hpd) and VO(gsal)(H2pt) have revealed distorted octahedral VO5N coordination. Six-membered and five-membered O,O chelation occur for Hpd- and H2pt-, respectively, an undissociated alcohol function lying trans to the oxo oxygen atom. The tridentate salicylaldimine ligand spans meridionally and has a folded structure consisting of two planar parts intersecting along a C-N bond. The V-O(alkoxide) bond in the complexes is ~0.6 &#197; shorter than the V-O(alcohol) bond. The alkoxidic chelate ring partially hydrolyzes in moist solventsthe six-membered ring in VO(Asal)(Hpd) more easily than the five-membered ring in VO(Asal)(H2pt). The hydrolysis is suppressed in the presence of the relevant free alcohol. The 51V NMR chemical shifts differ by ~20 ppm between VO(Asal)(Hpd) and VO(Asal)(H2pt) and are diagnostic of the alkoxidic chelate ring size. Species with chiral Asal2- ligands display diastereoisomeric equilibria in solution, and the equilibrium constants K = [endo]/[exo] have been determined from the 51V NMR signal intensity. The trend in K values is L-alanine &lt; L-phenylalanine &lt; L-valine (for given alkoxidic chelation) and Hpd- &lt; H2Pt- (for given amino acid residue). These trends are consistent with size effects. Crystal data are as follows. VO(gsal)(Hpd): chemical formula, C12H14NO6V; crystal system, monoclinic; space group, P21/n; a = 9.229(5), b = 12.655(6), c = 11.478(4) &#197;; &#946; = 99.61(4)&#176;; Z = 4. VO(gsal)(H2pt): chemical formula, C12H13NO7V; crystal system, monoclinic; space group, P21/c; a = 10.962(6), b = 9.544(4), c = 13.323(5) &#197;; &#946; = 102.67(4)&#176;; Z = 4

Carbohydrate binding to VO<SUP>3+</SUP>. Sugar vanadate esters incorporating L-amino acid schiff bases as coligands

The glycosides methyl-2,6-dimethoxy-&#946;-d-galactopyranoside (&#946;-d-H2Me3GP), methyl-4,6-dimethoxy-a-D-mannopyranoside (&#945;-D-H2Me3MP), and methyl-5-methoxy-&#946;-D-ribofuranoside (&#946;-d-H2Me2RF) have been synthesized, and their reaction with VO(L-Asal)(OMe)(OHMe) in dichloromethane has afforded esters of the type VO(&#946;-D-HMe3GP)(L-Asal), VO(a-D-HMe3MP)(L-Asal), and VO(&#946;-D-HMe2RF)(L-Asal) as dark-colored solids (red in solution). Here, L-Asal2- is the deprotonated salicylaldimine of L-alanine (A = a), L-valine (A = v), and L-phenylalanine (A = p). The X-ray structures of VO(&#946;-D-HMe3GP)(L-vsal)&#183;H2O and VO(a-D-HMe3MP)(L-psal)&#183;H2O have revealed five-membered (O,O)-chelation by monoionized carbohydrates, the undissociated hydroxyl group lying trans to the oxo oxygen atom. In the carbohydrate frame, the alkoxidic oxygen atom is axial in the former ester and equatorial in the latter. The V-O(alkoxidic) and V-O(alcoholic) distances are, respectively, ~1.80 and ~2.30 &#197;. The ONO coordinating tridentate salicylaldimine ligand is folded (by ~35&#176;) along a C-N bond. The chiral configuration of the metal site corresponds exclusively to the endo disposition of the V=O and the amino acid C-R (R = Me, CHMe2, CH2Ph) bonds. In VO(&#946;-D-HMe3GP)(L-vsal)&#183;H2O two ester molecules constitute the asymmetric unit and these along with the two water molecules form a macrocyclic supramolecule (diameter, ~6.1 &#197;) held by hydrogen bonds involving alcohol and an OMe function as well as water (O&#183;&#183;&#183;O distance, 2.59-2.86 &#197;). On the other hand, in VO(a-D-HMe3MP)(L-psal)&#183;H2O the water molecule bridges two symmetry-related ester molecules via alkoxide&#183;&#183;&#183;water and alcohol&#183;&#183;&#183;water hydrogen bonds forming an infinite chain structure (O&#183;&#183;&#183;O lengths, 2.65 and 2.85 &#197;). The molecular structures observed in the solid state are preserved in solution (1H and 51V NMR). No isomerization is detectable either at the metal site or at the anomeric carbon atom, and the V-O(alkoxidic) and V-O(alcoholic) sites and the metal-carbohydrate binding remain in tact. The VO(&#946;-D-HMe2RF)(L-Asal) species did not afford single crystals but NMR results are consistent with (O,O)-chelation by the ribose fragment, the alkoxidic carbon being C3. Crystal data are as follows. VO(&#946;-D-HMe3GP)(L-vsal)&#183;H2O: chemical formula, C21H32NO11V; crystal system, orthorhombic; space group, P212121; a = 13.146(7) &#197;, b = 15.142(5) &#197;, c = 25.631(9) &#197;; Z = 8. VO(a-d-HMe3MP)(L-psal)&#183;H2O: chemical formula, C25H32NO11V; crystal system, monoclinic; space group, P21; a = 13.645(4) &#197;, b = 7.022(2) &#197;, c = 15.500(4) &#197;; &#946; = 113.98(2)&#176;; Z = 2

Synthesis and structure of vanadate esters of glycerol and propane-1,3-diol

Complexes of the type [VO(L)(H2gl)] and [VO(L)(Hpd)] have been synthesized in excellent yields by reacting bis(acetylacetonato)oxovanadium(IV) with H2L in the presence of excess glycerol (H3gl) and propane-1,3-diol (H2pd) in methanol–acetone (hydroxyphenylmethylenehydrazones of 4-hydroxy-4-phenylbut-3-en-2-one, salicylaldehyde and 2-hydroxynaphthaldehyde are respectively abbreviated as H2L1, H2L2 and H2L3 and generally as H2L). The crystal structures of [VO(L2)(H2gl)] and [VO(L2)(Hpd)] have revealed tridentate ONO co-ordination by [L2]2– while [H2gl]– and [Hpd]– form five- and six-membered V(O,O) chelate rings respectively. In the distorted octahedral VO5N co-ordination sphere the V–O (alkoxide) bond is 0.5–0.6 Å shorter than the V–O (alcoholic) bond which lies trans to the oxo oxygen atom. In [VO(L2)(Hpd)] the lattice consists of dimers held together by O · · · N hydrogen bonding between the OH group of [Hpd]– in one molecule and the unco-ordinated [L2]2– nitrogen in an adjacent molecule. In the [VO(L2)(H2gl)] lattice such dimers self-assemble into an infinite pattern via additional O · · · O hydrogen bonding between the unco-ordinated OH group of [H2gl]– of one molecule with the co-ordinated alkoxidic oxygen of the adjacent molecule. In [VO(L)(H2gl)] both the metal site and the [H2gl]– ligand are chiral and the two equally abundant diastereoisomers are present in solution (1H NMR). The 51V chemical shifts are diagnostic of the alkoxidic chelate ring size: the shifts of [VO(L)(H2gl)] being ≈30 ppm downfield from that of [VO(L)(Hpd)]. The complexes have low VO3+–VO2+ reduction potentials