Conformations,vibrational spectra and force field of 1-methyl-2-(2′-pyridyl)benzimidazole: experimental data and density functional theory investigation in comparison with 2-(2′-pyridyl)benzimidazole

The molecular structure, conformational equilibria, vibrational spectra and molecular force field of 1-methyl-2-(2′-pyridyl)benzimidazole have been determined at the HF, MP2 and DFT/(B3LYP, BVP86) levels with 6-31+G(d,p) and TZVP basis sets. The torsional potentials for the rotation around the C1–C2 pivotal bond have been calculated at the B3LYP/6-31+G(d,p) and BVP86/TZVP levels of theory for gaseous and aqueous 1-methyl-2-(2′-pyridyl)benzimidazole. FT-Raman (3500–10 cm^?1) and FT-IR (3900–400 cm^?1) spectra of solid 1-methyl-2-(2′-pyridyl)benzimidazole have been recorded and interpreted on a base of calculated potential energy distribution. The results of the experimental and theoretical study of vibrational spectra and molecular structure of 1-methyl 2-(2′-pyridyl)benzimidazole are considered in comparison with similar data for 2-(2′-pyridyl)benzimidazole.

     

Syntheses,structures, and properties of transition metal complexes with 2-( n -pyridyl)benzimidazole ( n = 2, 3, and 4)

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH₃COO)₄] (1), [Cu(3-PBIM)₂(CH₃COO)₂]?·?2H₂O (2), [Cu(4-PBIM)₂(CH₃COO)₂(H₂O)]?·?H₂O (3), and [Fe(4-PBIM)₂(Cl)₂(H₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.     

Synthesis of 2-(2-Thienyl)benzimidazoles by the Reaction of 2-(Mercaptomethyl)benzimidazole With β-Electrophilic Esters

New 2-(2-di- and tetrahydrothienyl)benzimidazole compounds were prepared by the ring closure reactions of 2-(mercaptomethyl)benzimidazole^1,2 (1) and α,β-unsaturated compounds activated with electron-withdrawing groups.     

A copper(II) complex with 2-(2′-pyridyl)benzimidazole and l-arginine: synthesis,structure, antibacterial activities,and DNA interaction

A Cu(II) complex with 2-(2′-pyridyl)benzimidazole and l-arginine has been synthesized and investigated by elemental analysis, molar conductivity, IR, UV/vis, and X-ray diffraction. The complex crystallizes in the triclinic space group P1 with six molecules in a unit cell of dimensions a?=?10.6397(5)?Å, b?=?19.2178(8)?Å, c?=?20.0387(9)?Å, α?=?75.3670(10)°, β?=?79.4670(10)°, γ?=?87.4470(10)°, V?=?3897.6(3)?ų, R ₁?=?0.0408, and wR ₂?=?0.0502. The complex contains six crystallographically independent complexes, Cu1, Cu2, Cu3, Cu4, Cu5, and Cu6, which have a distorted square-pyramidal geometry. The complex was screened for its in vitro antibacterial activities against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella) micro-organisms. The complex exhibited good antibacterial activities against the micro-organisms compared with HPB and Cu(ClO₄)₂. Interaction of the complex with DNA was studied by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic spectroscopy, viscosity measurements, and agarose gel electrophoresis. Results suggest that the complex could bind to CT-DNA via partial intercalation, and cleave the plasmid DNA with involvement of hydroxyl radicals, and probably singlet oxygen-like copper-oxo species in the presence of ascorbate.     

A helical polymeric complex,tris(benzimidazole)nickel(II) (μ-maleato)

The title polymeric complex [Ni(C₇H₆N₂)₃(C₄H₂O₄)] _n has been prepared and its crystal structure determined by single-crystal X-ray diffraction methods. The complex is orthorhombic, space group P2₁2₁2₁ with a?=?9.320(1), b?=?12.015(1), c?=?20.964(2)?Å. Three benzimidazole (bzim) and two maleate dianions coordinate to the Ni(II) atom with distorted octahedral geometry. Maleate dianions bridge neighbouring Ni(II) atoms through terminal carboxyl groups, one in monodentate and the other in chelate mode, to form polymeric molecular chains extending along the a axis. The structure is chiral, the Flack index of 0.002(10) suggesting that the helical polymeric chain is right-handed. Both intra-helical and inter-helical N–H···O hydrogen bonding occurs between bzim and carboxyl groups of maleate. The partially overlapped arrangement of nearly parallel bzim rings suggests the existence of π–π stacking in the crystal.     

Reduction of olefins,nitroarenes and Schiff base compounds by a polymer-supported [2-(2′-pyridyl)benzimidazole]palladium complex

2-(2′-Pyridyl)benzimidazole (PBIMH) was functionalized onto chloromethylated polystyrene beads crosslinked with 6.5 % divinylbenzene, and this solid support was then reacted with Na₂PdCl₄ in methanol. The functionalized beads were then activated using sodium borohydride. The resultant polymer-supported [2-(2′-pyridyl)benzimidazole]palladium complex (PSDVB–PBIM–PdCl₂) and its activated form were characterized by various physicochemical techniques. XPS studies confirmed the +2 oxidation state of palladium in the supported complex. The activated complex was found to catalyse the hydrogenation of various organic substrates including olefins, nitro and Schiff base compounds. Kinetic measurements for the hydrogenation of cyclopentene, cyclohexene and cyclooctene were carried out by varying temperature, catalyst and substrate concentration. The energy and entropy of activation were evaluated from the kinetic data. The catalyst showed an excellent recycling efficiency over six cycles without leaching of metal from the polymer support, whereas the unsupported complex was unstable as metal leached out into the solution during the first run.     

Syntheses,spectroscopy, and catalysis of (η 4-cod)Rh(I)-complexes with (R or S)-2-(salicylaldimine)-2-phenylethanol or (rac)-2-(salicylaldimine)-1-phenylethanol

Condensation of salicyldehyde with (R or S)-2-amino-2-phenylethanol or rac-2-amino-1-phenylethanol gives enantiopure (R or S)-2-(salicylaldimine)-2-phenylethanol (R- or S-H₂L1) or (rac)-2-(salicylaldimine)-1-phenylethanol (rac-H₂L2). The Schiff bases coordinate to [Rh(η ⁴-cod)(μ-O₂CCH₃)]₂ to afford mononuclear [Rh(η ⁴-cod){(R or S)-2-(salicylaldiminato)-2-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(R- or S-HL1)] (1 or 2), or [Rh(η ⁴-cod){(rac)-2-(salicylaldiminato)-1-phenylethanol-κ ² N,O}], [Rh(η ⁴-cod)(rac-HL2)] (3). The Schiff base and complexes are characterized by IR-, UV/Vis-, ¹H/¹³C-NMR-, mass-spectroscopy, circular dichroism (CD), and polarimetry. The synthetic and spectroscopic results suggest that deprotonated Schiff base coordinates to [Rh(η ⁴-cod)] as a six-membered N,O-chelate with distorted square planar geometry at rhodium. CD and polarimetry measurements show the enantiopurity of the Schiff bases as well as the complexes in solution. The in situ system composed of [Rh(η ⁴-cod)Cl]₂ and S-H₂L1 has been used as a catalyst for the reduction of acetophenone into rac-1-phenylethanol with 85% conversion in diphenylsilane at 0–5°C.     

CRYSTAL AND MOLECULAR STRUCTURE OF 1-(4-DIMETHY-LAMINOPHENYL)-2- (3, 4-METHYLENE-DIOXYPHENYL ) ACRY-LONITRILE, C_(18)H_(16)N_2O_2

<正> C18H16N2O2, Mr = 292. 34, monoclinic space .group P21/c, a= 7.972(6), b = 6. 446(3), c=28.906(4)(?); β=95.59(8)°, V = 1478. 3(7)(?)3, Z = 4, Dx =1. 313 g/cm3, R = 0. 049. The non-hydrogen atoms of the title molecule are nearly co-planar forming a conjugation system.     

Synthesis of a dehydroabietyl derivative bearing a 2-(2'-hydroxyphenyl)benzimidazole unit and its selective Cu²+ chemosensing

A dehydroabietyl derivative 2 bearing a 2-(2'-hydroxyphenyl)benzimidazole unit was synthesized and its sensing behaviors toward metal ions were investigated by UV-Vis and fluorescence spectroscopy methods. In THF solution, compound 2 exhibited excellent selectivity for CuII over miscellaneous other metal ions including CrII, MnII, CoII, NiII, ZnII, CdII, AlIII, MgII, PbII, HgII, NaI, LiI and KI evidenced through the quenching of the fluorescence of the benzimidazole fragment. The reaction between 2 and Cu2+ was found to be stoichiometric with the formation of a 1:1 complex.     

Asymmetric Synthesis of (-)-(2R,3R,6S)-Irnigaine

Introduction　　Asarelativelynewmemberofnaturalalkaloidswith2 ,6 disubstituted 3 piperidinolskeleton ,irnigaine 1wasisolatedfromthetubersofArisarumVulgare (Araceae)in1995byMelhaouiandBode .1Itsstructureandrelativeconfigurationswereelucidatedby1HNMRstudiesandtheabsoluteconfigurationwasproposedonthebasisofitsopti calrotation .1Soonafterthen ,Meyerandhisco workersreportedthefirstsynthesisof (- ) (2R ,3R ,6S) irni gaineandtheconfigurationconfirmation .Althoughtheirsynthesisroutewasshortan…     

Synthesis and Crystal Structure of catena-Poly[bis-(benzimidazole)cobalt(Ⅱ) μ- Phthalato]

The title polymeric complex [Co(C8H4O4)(C7H6N2)2]n has been prepared and its crystal structure was determined by X-ray diffraction method. The crystal belongs to monoclinic,space group C2/c with a = 7.7865(12), b = 20.4215(18), c = 13.4880(14) (A),β = 103.298(2)°, V = 2087.3(4) (A)3, Mr = 459.32, Z = 4, Dc= 1.462 g/cm3,μ = 0.859 mm-1, F(000) = 940, R = 0.0636 and wR = 0.1639 for 1278 observed reflections (I ＞ 2σ(Ⅰ)). The complex assumes a distorted tetrahedral coordination geometry, formed by two phthalate anions and two benzimidazoles (bzim). The phthalate anions bridge the neighboring Co(Ⅱ) atoms to form the polymeric chains. The centroid distance of 3.471(3) (A) between the parallel bzim rings of adjacent polymeric chains suggests the existence of π-π stacking.     

Synthesis and Structural Determination of (2R,4S,SS)-( )-Threo-5-(2,2-dichloroacetamido)-4-(4-nitrophenyl)-2-aryl-1,3-dioxanes

Acetalscanbesynthesizedinanumberofways.Themainproblemintheacetalformationinacidicmediumistoshifttheequilibriumtotherightbyremovalofthewaterformedduringthereactionl.Wesynthesized(2R,4S,SS)-( )-threo-5-(2,2-dich(4-nitrophenyl)-2-aryl-1,3-dioxanesbyacet...     

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

(R)-(-y5-[(IR,2S,5R)-menthyloxy](1)isausefulchiralsynthonreadilypreparedonatWo-stepprocedure-l']FindingsoffuranoneringsexistingascomponentSofsomenaturalproductSI'laswellastheiractivereactivityl']havestimu1atedeXtensiveresearchofitSasymmetricreactionswhichincludeDiels-Alderreactions,l']l,3-dipo1arcycloadditions,['1Michaelauditionsl5]andconjugateedditionsofaminesl']andmercaPtans.g4:,::7f:7':theseadductsledtovariousmultifunctionalhomochiralbuildingblockssuchas2-alkyl-l,4-butanediols,I'l2-aI…     

5-羟基色胺受体激动剂(1R,2S)-(-)-2-(2-羟基苯基)-N,N-二丙基环丙胺的不对称合成

利用手性双唑啉与三氟甲磺酸亚铜催化2-甲氧基苯乙烯与重氮乙酸二环己基甲酯的不对称环丙烷化反应合成了手性环丙烷羧酸酯,用氢氧化钠对其进行选择性水解得到全反式环丙烷羧酸,其ee值经GC测定为88%.进一步经过Curtius重排、烷基化等反应及重结晶等步骤合成了光学纯的具有生理活性的环丙胺化合物1a和1b.     

Synthesis,thermal and spectral studies of oxoperoxo and dioxo complexes of vanadium(V), molybdenum(VI) and tungsten(VI) with 2-(α-hydroxyalkyl/aryl)benzimidazole

Reaction of 2-(-hydroxymethyl)benzimidazole or 2-(-hydroxyethyl)benzimidazole (LH) with the peroxovanadium(V) species, generated in situ by stirring V₂O₅, KOH and 30% aqueous H₂O₂, gives the corresponding complexes of formula K[VO(O₂)L₂]. Similar peroxo species of molybdenum and tungsten generated by stirring MoO₃ or WO₃·H₂O with an excess of 30% aqueous H₂O₂ readily react with 2-(-hydroxyethyl) benzimidazole in aqueous EtOH to give the peroxo complexes [MO(O₂)L₂] (M=Mo or W). The dioxo complexes of general formula [MO₂L₂] have also been isolated by the reaction of [MoO₂(acac)₂] or [WO₂- (acac)₂] (acacH=acetylacetone) with the above ligands and with 2-(-hydroxybenzyl)benzimidazole. The dioxo complexes are white, whereas peroxo complexes are light yellow to orange. The peroxo complexes generally decompose in two steps: (i) the decomposition of the peroxo group and (ii) the decomposition of the alkyl/aryl group followed by decomposition of the complete ligand. On the other hand, decomposition of the dioxo complexes follows only in a later step. All the peroxo complexes exhibit three i.r. active vibrational modes at ca. 860cm^–1, 760cm^–1 and 600cm^–1, characteristic of the ²-coordinated peroxo group. The dioxo complexes are dominated by the presence of two sharp bands in the 900cm^–1 region due to _sym(O=M=O) and _asym(O=M=O) modes. The (C=N) (ring) and (OH) shifts have also been measured in order to locate the coordination sites of the ligands. A broad band at ca. 400nm in the peroxovanadium(V) complexes, while the absorption at ca. 350nm in the peroxomolybdenum(VI) and tungsten(VI) complexes is assigned to the peroxo-metal charge transfer band.     

Hydrothermal Syntheses,Crystal Structures,and Characterization of Two Zinc(Ⅱ) Complexes Containing Flexible Bis(benzimidazole) Ligands

Two zinc(Ⅱ) complexes, namely, [Zn(L_1)Cl_2]_2(1) and {[Zn(L_2)(tbta)]·3H_2O}n(2)(L_1 = 1,3-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2 tbta = tetrabromoterephthalic acid, L2_ = 1,3-bis(2-methylbenzimidazol-1-yl)-2-propanol), have been successfully obtained under hydrothermal conditions. Complex 1 displays a binuclear structure which is further extended into a 1D supramolecular chain through π-π stacking. Complex 2 features a 2D(4,4) network based on a L2/tbta2- double linker. The thermal stability, fluorescence properties and catalytic activities of two complexes for the degradation of methyl orange in a Fenton-like process were discussed.     

Synthesis of 2-(hydroxyphenylamino)- and 2-(aminophenylamino)-4-methylquinolines and N,N′-bis(4-methylquinolin-2-yl)benzenediamines

2-(Hydroxyphenylamino)- and 2-(aminophenylamino)-4-methylquinolines and N,N′-bis(4-methylquinolin-2-yl)benzenediamines were synthesized by reactions of 2-chloro-4-methylquinolines with o-, m-, and p-aminophenols and o-, m-, and p-phenylenediamines.     

Synthesis,reactions, and antimicrobial activity of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide derivatives

Knӧvenagel condensation of the starting 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)-benzylidene)acetohydrazide with different aromatic aldehydes produced the comparable arylidenes derivatives. Else way, 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)-benzylidene)-acetohydrazide condensed with o-hydroxybenzaldehydes affording the respective chromenes which latter underwent acid hydrolysis giving the oxo-chromenes analogues. Moreover, the reaction of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide with istain yielded the respective indeno[2,1-b]furan derivative that was converted to its oxo-analogue through acid hydrolysis. The treatment of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide with α-halocompounds produced the relevant thiazoles. The enamine 2-cyano-3-(dimethylamino)-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acrylohydrazide underwent nucleophilic substitution reaction with guanidine hydrochloride followed by heterocyclization to get the relative aminopyrimidine. Contrarily, the reaction with various 4-arylazo-3,5-diaminopyrazoles provided the relative pyrazolo[1,5-a]pyrimidines. The antimicrobial investigation was carried out for some of the newly synthesized compounds using agar well diffusion method.     

Complexation of sym-bis(benzimidazole)-2, 2’-ethylene salts with cucurbit[6]uril derivatives：A potential axle molecule for pseudorotaxanes

Sym-bis(benzimidazole)-2,2'-ethylene cations act as a new axle template for threading cucurbit[6]uril derivatives on, forming [2]pseudorotaxane and [3]pseudorotaxane. These new complexes have been studied using 1H NMR, UV-vis absorption spectroscopy and X-ray analysis. Changes in the 1H NMR spectra indicate that the two types of pseudorotaxane can be formed by varying the host concentration. UV-vis absorption titration experiments at different pH values demonstrate that interesting pKa shifts of the bis-benzimidazole derivatives can be induced by the host-guest complexation. The associated constants were calculated to be 2.81×104 L/mol and 9.06×106 L/mol for the [2]pseudorotaxanes and [3]pseudorotaxanes, respectively. Furthermore, X-ray diffraction studies of the solid state structures provide unequivocal proof of the host concentration dependent pseudorotaxane, which is strongly in line with the evidences in solution.