Crystal structure,optical properties,and theory study of a 1-D bromoplumbate stabilized by in situ generated N-alkylated DABCO cation

We report the exploration of the stabilization effect of the in situ generated N-alkylated DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane) cation in the family of bromoplumbates and a 1-D bromoplumbate, (Et₂DABCO)_2n(Pb₃Br₁₀)_n (1), has been prepared by solvothermal conditions. Optical diffuse reflectance determination shows the band gap of 1 is 3.69 eV, which manifests that 1 is a wide band gap semiconductor. Compared with the band gap of bulk PbBr₂ (3.84 eV), 1 exhibits 0.15 eV red shift of absorption edge. While for the reported iodo analogs of this compound, (MPDA)_2n(Pb₃I₁₀)_n and (Et₂DABCO)_2n(Pb₃I₁₀)_n, they exhibit 0.53 and 0.47 eV blue shift of the energy gaps compared with the measured value of 2.30 eV for bulk PbI₂, respectively. The photoluminescent study of 1 shows that it exhibits a broad emission band centered at 697 nm upon photoexcitation by 345 nm (amount to 3.59 eV). The calculated density of states manifests the theoretical value of the band gap of 1 is 3.422 eV and the origination of photoluminescence can be ascribed to the transition of bonding electrons of Br^– anion to the empty orbits of Pb(II) ion.     

Cobalt(II) porphyrin axially coordinated with 2′-(pyridin-4-yl)-5′-(pyridin-2-yl)-1′-(pyridin-2-ylmethyl)-2′,4′-dihydro-1′H-pyrrolo[3′,4′ : 1,2](C60-Ih)[5,6]fullerene: formation,chemical structure,and spectroscopic properties

Construction of new effective photovoltaic devices based on organic dyes has important implications for modern and future technologies. In this article, we studied the equilibrium, the rate, and the spectral manifestation of the reaction of [(2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(2-pyridyl)porphyrinato)cobalt(II)]–[2′-(pyridin-4-yl)-5′-(pyridin-2-yl)-1′-(pyridin-2-ylmethyl)-2′,4′-dihydro-1′H-pyrrolo[3′,4′ : 1,2](C₆₀-I_h)[5,6]fullerene] triad formation as well as its spectral properties and photo electrochemical behavior. The cobalt porphyrin–pyridyl-substituted fullerene mixtures in toluene are self-assembling systems due to axial donor–acceptor binding between Co of the porphyrin complex and N-pyridyl of the substituted fullerene. The formation rate constant, k^298K, and the stability constant, K^298K, of donor–acceptor triad formed by coordination of two substituted fullerene molecules to Co porphyrin are (44.4 ± 0.8) mol L^?1 s^?1 and (56 ± 16)×10⁷ L² mol^?2, respectively. Modification of the titanium electrode coated with the natural oxide film was carried out using the porphyrin–fullerene triad and its individual components. Photopotential and photocurrent density of the system with modified electrode were studied. The obtained results are of interest for creating porphyrin-based donor–acceptor systems as components in organic photovoltaics.     

New complexes of Zn(II) with the anti-inflammatory non-steroidal drug,ibuprofen and nitrogen donor ligands. Synthesis,characterization and biological activity

Complexes of [Zn(ibup)₂(4,4′-bipy)]_n 1, [Zn(ibup)₂(phen)] 2, [Zn(ibup)₂(2,9-dmphen)] 3, [Zn(ibup)₂(1,2-dmimidazole)₂] 4, and [Zn(ibup)₂(2-am-6-picoline)₂] 5 (ibu = ibuprofen, 4,4′-bipy = 4,4′-bipypyridine, phen = 1,10-phenanthroline, 2,9-dmephen = 2,9-dimethyl-1,10-phenanthroline, 1,2-dmimidazole = 1,2-dimethylimidazole, and 2-am-6-picoline = 2-amino-6-picoline) were prepared and characterized. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The in vitro anti-bacterial activities for the complexes against Gram-positive (Micrococcus luteus, Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumonia and Proteus mirabilis) bacteria were done using the agar well-diffusion method. Complexes 1–3 showed anti-bacterial activity against Gram-positive bacteria, while 4 and 5 did not exhibit anti-bacterial activity. Complexes 2 and 3 were selected for further studies. Complexation of zinc-ibuprofen with phen as in 2 decreased the anti-bacterial activity against most of the bacteria used. The complexation in 3 decreased the anti-bacterial activity in Gram-positive bacteria but for Gram-negative bacteria, the overall anti-bacterial activity of uncoordinated 2,9-dmphen was enhanced upon coordination with zinc ibuprofen.     

Synthesis,characterization and biological properties of novel ON donor bidentate Schiff bases and their copper(II) complexes

Four novel ON donor Schiff bases (E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol (HL₁),(E)-3-((4-(4-biphenyloxy)phenyliminomethyl)benzene-1,2-diol (HL₂), (E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol (HL₃), (E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol (HL₄) and their copper(II) complexes bis((E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₁)₂) bis((E)-3-((4-(4-biphenyloxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₂)₂), bis((E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₃)₂), bis((E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₄)₂) have been synthesized and characterized by spectroscopic (FTIR, NMR, UV–visible) and elemental analysis. The crystal structures of HL₁, HL₂, HL_3, and HL₄ have been determined, which reveal intramolecular N-H?O (HL₁, HL₂, HL_3, and HL₄) hydrogen bonds in the solid state. Keto-amine and enol-imine tautomerism is exhibited by the Schiff bases in solid and solution states. The Schiff bases and their copper(II) complexes have been screened for their biological activities. In antimicrobial assays (antibacterial and antifungal), HL₄ showed promising results against all strains through dual inhibition property while the rest of the compounds showed activity against selective strains. On the other hand, in cytotoxic, DPPH, and inhibition of hydroxyl (OH) free radical-induced DNA damage assays, the results were found significantly correlated with each other, i.e. the ligands HL₁ and HL₂ showed moderate activity while their complexes Cu(L₁)₂ and Cu(L₂)₂ exhibited prominent increase in activity. As the results of these assays are supporting each other, it represents the strong positive correlation and antioxidant nature of investigated compounds.     

Pyridoxylidene aminoguanidine and its copper(II) complexes – Syntheses,structure, and DFT calculations

Two nitrate salts of the well-known, and due to its significant biological activity very important, compound pyridoxylidene aminoguanidine (PLAG) were obtained in the form of single crystals. Thus this ligand is structurally characterized for the first time. In addition, the first data on the structure of a Schiff base of aminoguanidine with the active form of vitamin B₆, i.e. pyridoxal-phosphate, of the formula PLPAG·HCl·2H₂O, are presented. Two new square-pyramidal Cu(II) complexes of PLAG were synthesized and their physicochemical and structural properties analyzed. In these complexes, PLAG is coordinated as a zwitter-ion, in a tridentate ONN manner, via the oxygen atom of the deprotonated phenolic OH-group and nitrogen atoms of the azomethine and imino group of the aminoguanidine moiety. For the first time it was possible to make a comparative analysis of the structural properties of ligand salts and the coordinated ligand, so the effects of coordination could be unequivocally pointed out. Common fragments encountered in ligand structures were compared by half-normal probability plots. Density functional theory calculations have been conducted in order to gain insight into reactive properties of the investigated molecules. Molecular electrostatic potential, average local ionization energy surfaces, and Fukui functions have been calculated in order to obtain further information on the reactive properties.     

Synthesis and in vitro cytotoxicity of novel dinuclear platinum(II) complexes containing a chiral tetradentate ligand

A series of novel dinuclear platinum(II) complexes with a chiral tetradentate ligand, (1R,1′R,2R,2′R)-N¹,N¹′-(1,2-phenylenebis(methylene))dicyclohexane-1,2-diamine (HL), and mono-carboxylic acid derivatives as ligands have been designed, synthesized, and characterized. In vitro cytotoxicity evaluation of synthesized complexes against human HepG-2, A549, HCT-116, and MCF-7 cancer cell lines has been conducted by MTT assays. All compounds showed antitumor activity to HepG-2 and HCT-116 cell lines. Compound L2 exhibited better cytotoxicity than that of carboplatin against HepG-2 and A549 cell lines and also showed comparable activity against HCT-116 cell line.     

Multinuclear (Sn/Pd) complexes with disodium 2,2′-(dithiocarboxyazanediyl)diacetate hydrate; Synthesis,characterization and biological activities

Bimetallic chlorodi-/triorganotin(IV) derivatives of general formulas R₂(H₂O)SnLCSSSn(Cl)R₂ (R=Me: 1; Ph: 2) and R₃Sn(Na)LCSSSnR₃·H₂O (R=Bu: 3; Ph: 4) were prepared by reaction of iminodiacetic acid disodium salt hydrate (Na₂LH) with CS₂ and R₂SnCl₂/R₃SnCl in methanol. The reaction between Na₂LH, CS₂, and PdCl₂ produced [Na₂LCSS]₂Pd·2H₂O (5) which was treated with R₃SnCl to synthesize the heterobimetallic derivatives [R₃Sn(Na)LCSS]₂Pd·2H₂O (R=Me: 6; Ph: 7). The complexes were characterized by microanalysis, spectroscopic, and thermogravimetric analyses. Elemental analysis data, mass fragmentation, and thermal degradation patterns supported the molecular composition of the complexes. FT-IR data indicated monodentate binding of carboxylate while a chelating coordination mode of the dithiocarboxylate was verified in the solid state. A five-coordinate tin(IV) was demonstrated in the solid state. In solution, a tetrahedral/trigonal bipyramidal configuration around Sn(IV) and a square planar geometry of Pd(II) was indicated by multinuclear NMR (¹H and ¹³C) and UV-visible studies. The Pd(II) derivatives showed interaction with salmon sperm-DNA and caused an inhibition of alkaline phosphatase (ALPs). The antibacterial/antifungal potential of the coordination products varied with the nature of incorporated metal and a substitution pattern at tin(IV); the palladium metallation decreased the antimicrobial activities. The triorganotin(IV) products exhibited more powerful action against bacteria/fungi as compared to their diorganotin(IV) counterparts. The complexes displayed sufficiently lower hemolytic effects in vitro as compared to triton X-100 and slightly higher than PBS.     

Polymerizations of methyl methacrylate and rac-lactide by zinc(II) precatalyst containing N-substituted 2-iminomethylpyridine and 2-iminomethylquinoline

The reaction of [ZnCl₂] with N-cyclopentyl-1-(quinolin-2-yl)methanimine (L_A), N-cyclohexyl-1-(quinolin-2-yl)methanimine (L_B), N-cyclohexyl-1-(pyridin-2-yl)methanimine (L_C), 2,6-diethyl-N-(pyridin-2-ylmethylene)aniline (L_D), N-cyclopentyl-1-(pyridin-2-yl)methanimine (L_E), and N-phenyl-(pyridin-2-yl)methanimine (L_F) in ethanol produced the bidentate [(NN′)ZnCl₂] complexes, [L_AZnCl₂], [L_BZnCl₂], [L_CZnCl₂], [L_DZnCl₂], [L_EZnCl₂] and [L_FZnCl₂], respectively. The molecular structures revealed that the zinc in [L_nZnCl₂] (L_n = L_A ? L_D) showed a distorted tetrahedral geometry involving two nitrogens of N,N’-bidentate ligands and two chloride ligands. Most of these initiators were effective for polymerization of methyl methacrylate (MMA) and polymerization of rac-lactide (rac-LA). [L_CZnCl₂] (with N-cyclohexyl substituted at imine-pyridine moiety) exhibited the highest catalytic activity for MMA polymerization in the presence of modified methylaluminoxane (MMAO) with an activity of 3.33 × 10⁴ g PMMA/mol·Zn·h at 60 °C, giving moderate syndiotactic poly methyl methacrylate (PMMA) with high molecular weight (9.62 × 10⁵ g/mol). The dimethyl derivatives [L_nZnMe₂] (L_n = L_A ? L_F), generated in situ, polymerized rac-LA with moderate activity and yielded a polylactide (PLA) with good number-average molecular weights and narrower polydispersity indices (PDIs). [L_AZnMe₂] effectively initiates the ring-opening polymerization (ROP) of rac-LA to attain heterotactic PLA (P_r = 0.91).     

Synthesis and Structures of Gallium‐β‐Diketiminate Complexes: Isolation of a Dinuclear Gallium(II) Complex

The sterically demanding β‐diketiminate ligand L^dmp [L^dmp = HC{(CMe)N(dmp)}₂, dmp = C₆H₃‐2,6‐Me₂] was used to stabilize various gallium complexes in the formal oxidation states +II and +III. The reaction of in situ generated [L^dmpLi] with gallium chloride affords [L^dmpGaCl₂] ( 1 ), which was used as starting complex to synthesize a variety of gallium(III) compounds [L^dmpGaX₂] [X = F ( 2 ), I ( 3 ), H ( 4 ), and Me ( 5 )]. Synthesis of the dinuclear complex [L^dmpGaI]₂ ( 6 ), with gallium in the formal oxidation state +II was accomplished by converting “GaI” with in situ generated [L^dmpLi] in toluene. All compounds were characterized by elemental analyses, NMR spectroscopy, LIFDI‐TOF‐MS, and single‐crystal X‐ray diffraction. Additionally DFT calculations were performed for analysis of the bonding in 6 .     

A Potential Method Using Ge{iPrNC[N(SiMe3)2]NiPr}2, (Et3Si)2Te and Anhydrous Hydrazine for Germanium Tellurides

A germanium(II)‐guanidine derivative of formula Ge{iPrNC[N(SiMe₃)₂]NiPr}₂ ( 1 ) was synthesized and characterized by ¹H NMR, ¹³C NMR, elemental analysis, and X‐ray diffraction method. Thermal property was also studied to identify its thermal stability and volatility. More importantly, compound 1 was synthesized to develop a new method for germanium tellurides, where anhydrous hydrazine was introduced to prompt the activity of germanium(II) guanidines (or derivatives) towards (Et₃Si)₂Te. Solution reaction of compound 1 , (Et₃Si)₂Te, and anhydrous hydrazine was investigated to pre‐identify the feasibility of this combination for ALD process. The EDS data of the black precipitate from this reaction verified the potential of this method to manufacture germanium tellurides.