Ruthenium(II) complexes with 2-(benzylimino-methyl)-4-R-phenol containing the trans(PPh3),cis(CO,Cl)-{Ru(PPh3)2(CO)Cl} unit

Reactions of [Ru(PPh₃)₃Cl₂] with 2-(benzylimino-methyl)-4-R-phenol (H^RL, R = H, Cl, Br and OMe) in boiling methanol in presence of triethylamine afford ruthenium(II) complexes of general formula [Ru(^RL)(PPh₃)₂(CO)Cl] in 57-64% yield. Microanalysis, spectroscopic (infrared, electronic and NMR) and cyclic voltammetric measurements have been used for the characterization of the complexes. Crystal structures of two representative complexes have been determined by X-ray crystallography. The carbonyl, the chloride, the N,O-donor ^RL⁻ and the two mutually trans PPh₃ molecules assemble a distorted octahedral CClNOP₂ coordination sphere around the metal centre in each complex. The complexes display the Ru(II) → Ru(III) oxidation in the potential range 0.62-1.16 V (vs. Ag/AgCl).     

Segregated aromatic π-π stacking interactions involving fluorinated and non-fluorinated benzene rings: Cu(py)2(pfb)2 and Cu(py)2(pfb)2(H2O) (py = pyridine and pfb = pentafluorobenzoate)

The syntheses, physical characterization and crystal structures of two new molecular copper(II) complexes of composition [Cu(C₅H₅N)₂(C₇F₅O₂)₂] (1) and [Cu(C₅H₅N)₂(C₇F₅O₂)₂(H₂O)] (2) (C₅H₅N = py = pyridine and C₇F₅O₂⁻ = pfb = pentafluorobenzoate) are reported. Single-crystal X-ray structure determinations revealed that in 1, the Cu²⁺ ion, which lies on a crystallographic inversion centre, is coordinated to two py molecules and two oxygen atoms from two monodentate pfb anions, resulting in a trans-CuN₂O₂ square planar geometry. In 2, the Cu²⁺ ion is also coordinated to two py and two pfb species in addition to a water molecule in the apical site of a distorted CuN₂O₃ square pyramid. In the crystal packing, both 1 and 2 show segregated aromatic π-π stacking interactions in which (py + py) and (pfb + pfb) ring-pairings are seen, but no (py + pfb) pairings occur. Crystal data: 1: C₂₄H₁₀CuF₁₀N₂O₄, M_r = 643.88, space group , a = 8.0777 (3) Å, b = 8.0937 (3) Å, c = 10.5045 (5) Å, α = 90.916 (3)°, β = 93.189 (2)°, γ = 118.245 (3)°, V = 603.36 (4) Å³, Z = 1. 2: C₂₄H₁₂CuF₁₀N₂O₅, M_r = 661.90, space group , a = 7.5913 (5) Å, b = 15.6517 (6) Å, c = 21.1820 (14) Å, α = 95.697 (4)°, β = 94.506 (2)°, γ = 91.492 (4)°, V = 2495.2 (3) Å³, Z = 4.     

1-(d-Glucopyranosyl-2′-deoxy-2′-iminomethyl)-2-hydroxybenzene as chemosensor for aromatic amino acids by switch-on fluorescence

A glucose based C2-glyco-conjugate, that is, 1-(d-glucopyranosyl-2′-deoxy-2′-iminomethyl)-2-hydroxybenzene (L), has been synthesized in a high yield and characterized. Titration of L with all the 20 naturally occurring amino acids resulted in a large fluorescence intensity enhancement only in case of aromatic amino acids, that is, Phe, Trp, His, and Tyr and not with the others. This has been attributed to the initial formation of 1:1 hydrogen bonded complex followed by π-π interactions present between the aromatic moieties of such complexes as demonstrated by absorption and computational methods. Thus L has been able to recognize aromatic amino acids down to 1.5-3 ppm through switch-on fluorescence behavior.     

Cation-π interactions of curved polycyclic systems: M (M=Li and Na) ion complexation with buckybowls

B3LYP/6-311+G** calculations on alkali metal ion (Li⁺ and Na⁺) complexation with corannulene and sumanene indicate stronger binding compared to [5]-radialene or benzene. The dependence of binding to the convex and concave site is marginal, albeit the preference was consistent for convex binding in the range of 1-4 kcal/mol. The bowl-to-bowl inversion barriers are only marginally affected, below 2 kcal/mol, by metal ion complexation.     

Synthesis and Structure of a Novel Macrocyclic Complex [Cd2(phen)4(phth)2]·4H2O

A novel complex [Cd2(phen)4(phth)2]·4H2O has been synthesized by the reaction of H2phth(phthalic acid) and phen(1,10-phenanthroline) with Cd(Ⅱ) in ethanol-water solution. X-ray crystal structure analysis shows it crystallizes in triclinic, space group P1 with a = 10.619(3), b =12.560(4), c = 12.651(4) A, α = 98.775(5), β = 109.035(5), γ = 113.576(5)°, C32H24CdN4O6, Mr=672.95, V= 1381.7(7) A3, Rint = 0.0358, Z= 2, Dc= 1.618 g/cm3, μ = 0.845 mm-1, -6 ≤h≤13, -15≤k ≤13, -15≤l≤14, F(000) = 680, S = 1.038, R = 0.0480 and wR = 0.0849 for 3992 observed reflections (I ＞ 2σ(Ⅰ)). Phth bridges Cd(Ⅱ) to form a macrocyclic compound, and a 2D supramolecular motif is formed through hydrogen bonds and π-π interaction.     

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

1 INTRODUCTION Chemists have recognized that intermolecular inter- actions are the basis of functional properties for most molecular assembles, and detailed understan- ding of non-covalent chemistry is therefore funda- mental to interpreting and predicting the relation- ship between structure and function. Among intermo- lecular interactions, the π-π stacking between aro- matic rings is correlated with the electron transfer process in some biological systems[1], and the nature of π-π s…     

Synthesis of novel oxazaborolidines B-C6F5 and their effectiveness as asymmetric catalysts

Novel oxazaborolidines B-C₆F₅ were synthesized by modified protocol from C₆F₅B(OMe)₂ (in place of usual C₆F₅B(OH)₂) and the corresponding amino alcohols, aiming to know the π-π stacking and electron-withdrawing effects of C₆F₅ group in asymmetric reduction of ketones. Although the results were not simply explained by the expected effects, significant difference was observed in the enantioselectivity between the catalysts with B-C₆H₅ and B-C₆F₅.     

Synthesis and Crystal Structure of [Zn(FcCOO)_2(2,2'-bipy)(H_2O)]_2·H_2O

A novel complex [Zn(FcCOO)2(2,2'-bipy)(H2O)]2·H2O (Fc = (η5-C5H5)Fe(η5-C5H4), 2,2'-bipy = 2,2'-bipyridine) has been synthesized and characterized by elemental analysis, IR and X-ray diffraction. It crystallizes in monoclinic system, space group P21/c with a = 6.8187(4), b = 21.7155(13), c = 19.7411(12) A, α = 90, β = 97.7420(10), γ = 90o, C64H58Fe4Zn2N4O11, Mr = 1413.28, V = 2896.4(3) A3, Dc = 1.620 g/cm3, Z = 2, F(000) = 1444, μ(MoKα) = 1.857 mm-1, R = 0.0523 and wR = 0.0982 for 3219 observed reflections (I > 2σ(I)). Structural analysis shows that the zinc atom is coordinated with three oxygen atoms from two ferrocenemonocarboxylates and one water molecule together with two nitrogen atoms from 2,2'-bipyridine, giving a distorted square-pyramidal coordination geometry. The complex molecules are linked to form an infinite one-dimensional chain by both intermolecular hydrogen bonds and π-π stacking interactions of the bipyridine rings.     

SYNTHESIS AND OPTICAL PROPERTIES OF POLY (THIENYLACETYLENES)*

3 -Ethynyl-4-(trimethylsilyl)thiophene (1a) and 3 -ethynyl-4-bromothiophene (1 b ) selectivelyundergo acetylene polymerizations in the presence of the MoCl_5- and WCl_6-Ph_3SiH catalysts to give soluble,high-molecular-weight poly(thienylacetylenes) (2) (M_w up to 602000) in high yields (up to 100%). Lighttransmission spectra of THF solutions of 2 continuously red-shift with increasing concentration. Theconcentratochromism shows a logarithmic concentration dependence; that is, the optical transitions of 2 arepredictably tunable by simply changing their concentrations.     

用原子力显微镜4π旋转技术测量靶丸表面粗糙度

 原子力显微镜靶丸4π旋转装置,可以将靶丸在夹持状态下实现4π方向旋转,便于原子力显微镜对靶丸表面任一部分做扫描测量。应用该装置对各种靶丸的表面形貌进行了测量,测量结果表明,靶丸外表面粗糙度小于10nm,内表面粗糙度小于20nm。