Self-assembly of a fluorescent chiral zinc(II) complex that leads to supramolecular helices

The chiral Zn(II) complex [ZnLCl(2)], 1 {L = 4-methyl-2,6-di[(S)-(+)-1-phenylethyliminomethyl] phenol}, self-assembles via C-H...Cl hydrogen bonding into supramolecular helices. Complex 1 exhibits emission in solution at room temperature in the visible range. Crystal data for 1: orthorhombic space group P2(1)2(1)2(1), a = 9.614(2) A, b = 13.825(3) A, c = 18.667(3) A, V = 2481.1(8) A(3), Z = 4.     

A carboxyl porphyrin zinc(II)–copper(II) supramolecular system with fluorescence strengthening properties

The supramolecular self-assembly behavior, by hydrogen-bonding, of zinc(II) [Zn(p-CPTPP)], copper(II) [Cu^II-(p-CPTPP)] complexes [(p-CPTPP) = 5-(p-carboxyl)-phenylene-methanamidophenyl-10,15,20-triphenylporphyrin] were studied by fluorescence spectroscopic titration and by u.v.–vis. spectra. The fluorescence strengthening character was observed in the Zn(p-CPTPP)/Cu^II(p-CPTPP) system in a fluorescence spectroscopic titration experiment. The formation constant was determined from the fluorescence spectroscopic titration data and the fluorescence strengthening property of the system was discussed using the fluorescence spectrum of the charge-separated state obtained by the method of spline wavelet least squares.     

Synthesis and peptide-binding properties of a luminescent pyrimidine zinc(II) complex

The synthesis and peptide-binding properties of a Zn(II)nitrilotriacetate complex substituted with pyrimidine hydrazine amides are reported. The metal complex provides millimolar binding affinity in aqueous buffer to peptides bearing N-terminal His. The pyrimidine heterocycles intermolecularly interact with the bound peptide and quench the emission of nearby Trp residues by energy transfer.     

X-ray structural study of a zinc(II) inclusion complex of a phenolate-pendant cyclam

The molecular structure of phenol-pendant cyclam-zinc(II) complex,4a, has been determined by X-ray structure analysis. Crystals of4a · ClO₄ · CH₃OH (C₁₆H₂₇N₄OZn · ClO₄ · CH₃OH) are monoclinic, space groupP2₁/nn, with four molecules in the unit cell of dimensionsa=31.198(2) Å,b=8.426(1) Å,c=8.214(1) Å, and=93.96(1)°. The structure was solved by the heavy atom method and refined anisotropically toR=0.044,R _w=0.062 for 1551 independent reflections. The complex assumes a five-coordinate, square pyramidal geometry, where zinc(II) is surrounded by the cyclam moiety in a planar fashion with the pendant phenolate anion occupying an axial position. An extremely short Zn-O(phenolate) bond distance of 1.983(5) Å, in conjunction with the 0.288 Å displacement of Zn(II) above the cyclam N₄ plane toward the phenolate, accounts for the extremely low pK _a value of 5.8 for the pendant phenol. These facts about4a, in comparison with the previous findings for the Ni(II) (4b) and Cu(II) complexes (4c) with the same ligand, illustrate well the characteristics of zinc(II) ion coordination properties.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

羧基卟啉锌-铜超分子体系的荧光增强特性

通过稳态荧光光谱滴定和紫外-可见光谱考察了5-(对羧基苯基-甲酰氨基)苯基10，15，20-三苯基卟啉(p-CPTPP)锌(Ⅱ)、铜(Ⅱ)配合物体系通过氢键的超分子自组装行为。在荧光光谱滴定中，当Cu(p-CPTPP)浓度在一定范围内时，随着Cu(p-CPTPP)浓度增大，Zn(p-CPTPP)-Cu(p-CPTPP)体系荧光强度逐渐增大并稍有红移。根据荧光光谱滴定数据计算了超分子的结合常数，由小波变换方法分解得到的超分子电荷分离态荧光光谱解释了体系荧光增强现象。     

Blue-emitting mesoporous films prepared via incorporation of luminescent Schiff base zinc(II) complex

Highly fluorescent materials have been prepared by incorporation of a zinc complex in mesoporous silica thin films with ordered pore structure. The zinc complex has been introduced into the mesoporous materials via impregnation in an ethanol solution. The incorporation into the films has been monitored by UV–Vis, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. After 18 h of immersion in the doping solution the films showed strong blue emission, increase in the refractive index. Leaching experiments performed by immersing the samples in ethanol or tetrahydrofuran have shown that the chromophore is retained in the porous matrix.

Polyorganosiloxane-europium (III) host-guest inclusion system and its energy transfer luminescence

The Eu(III) ion, as a luminescent probe, is incorporated into a novel nanotube-contained polyorganosiloxane (POS), which is obtained by coupling of ladderlike polyvinylsilsesquioxane (Vi-T) with tetramethyldisiloxane (H-MM) via hydrosilylation, to form POS-Eu(III) composite. The results from fluorescent study demonstrate that the composite is actually a host-guest clathrate which includes the Eu(III) ions in the tubelike cavity of POS and moreover, the supramolecular clathrate exhibits an obvious energy transfer process which converts the UV light absorbed by POS into the visible light generated from the Eu(III) luminescence. Molecular simulation also gives support to the formation of such a clathrate and thus results in energy transfer process. Project supponed by the Research Foundation of Molecular Science Center and Director of Institute of Chemistry, the Chinese Academy of Sciences, and Foundation of Organic Solid Laboratory, the Chinese Academy of Sciences.     

m-Benziporphodimethene: a new porphyrin analogue fluorescence zinc(II) sensor

m-Benziporphodimethene is presented here as a long-wavelength Zn2+ specific chemosensor; this sensor shows fluorescence switch-on upon Zn2+ binding with no apparent background fluorescence.     

Self-assembly and crystal structure of a three-dimensional copper(II) complex

A copper(II) complex of a sulfonate derivative of chrysin, 5,7-bihydroxyflavone-6-sulfonate, Cu(C₁₅H₈O₇S)(3H₂O), has been prepared. The complex was characterized by elemental analysis, spectroscopic measurements and single-crystal X-ray diffraction studies. It crystallizes in the monoclinic space group C2/c, with a?=?16.036(18), b?=?6.944(8), c?=?28.03(3)?Å, β?=?94.463(17)°, V?=?3112(6)?ų, Z?=?8. In the complex, Cu(II) is five-coordinate and all donors are oxygen atoms. Hydrogen bonds and π–π stacking interactions in the crystal lead to the formation of a three-dimensional supramolecular motif.     

DNA photocleavage by a supramolecular Ru(II)-viologen complex

A novel Ru(II) complex possessing two sequentially linked viologen units, Ru-V(1)-V(2)(6+), was synthesized and characterized. Upon excitation of the Ru(II) unit (lambda(exc) = 532 nm, fwhm approximately 10 ns), a long-lived charge-separated (CS) state is observed (tau = 1.7 micros) by transient absorption spectroscopy. Unlike Ru(bpy)(3)(2+), which cleaves DNA upon photolysis through the formation of reactive oxygen species, such as (1)O(2) and O(2)(-), the photocleavage of plasmid DNA by Ru-V(1)-V(2)(6+) is observed both in air and under N(2) atmosphere (lambda(irr) > 395 nm).     

Spin transition in a chainlike supramolecular iron(II) complex

A one-dimensional supramolecular head-to-tail N+ -H...N-type hydrogen-bonded chain of the complex [FeII(L)2H](ClO4)3.MeOH [L = 4'-(4'-pyridyl)-1,2':6'1'-bis(pyrazolyl)pyridine] exhibits a reversible, thermally driven spin transition at 286 K with a hysteresis loop of ca. 2 K.     

Self-assembly of supramolecular Ni(II) and Cu(II) metalmacrocyclic compounds with tetraazamacrocyclic ligand into a gelatin-immobilized matrix

Self-assembly in M(II)-ethanedithioamide [H₂N–C(=S)–C(=S)–NH₂]-propanone triple systems (M=Ni, Cu) into corresponding metal(II) hexacyanoferrate(II) gelatin-immobilized matrix systems under contact with aqueous-alkaline (pH?～?12) solutions containing ethanedithioamide and propanone have been studied. Formation of supramolecular macrotetracyclic compounds of Ni(II) and Cu(II) with 2,7,7,9,14,14-hexamethyl-3,6,10,13-tetraazacyclotetradecadien-2,9-tetrathione-4,5,11,12 containing original “kernel” (metal complex) and “shell” surrounding this “kernel”, of polypeptide chains of the gelatin molecules, occurs under such specific conditions.     

Design of a zinc(II) ion specific fluorescence sensor

We report the synthesis of {[3-(biscarboxymethylamino)-2-methoxy-5-methylphenyl]carboxymethylamino}acetic acid, which functions as a Zn²⁺ selective fluorescence probe (sensor).     

Cu(II)-triggered release of paclitaxel from a supramolecular complex

The research on the stimuli-responsive property of biological or synthetic macromolecules in a wide range of scientific fields is a crucial subject for the achievements of the targeted drug release and the precise control of the functions of the supramolecules at a molecular level. We used an anthraquinone-functioned cyclodextrin (1) bridged by an aza-arm to solubilise paclitaxel (PTX) by forming a supramolecular complex (1/PTX). The possible inclusion mode was given based on the experimental results of ultraviolet–visible spectroscopy, Fourier transform infrared, X-ray diffraction, fluorescence spectra, nuclear magnetic resonance, transmission electron microscope, scanning electron microscope and dynamic light scattering characterisations. The controlled release of PTX can be achieved by adding Cu²⁺ to the solution. This study provides useful references in developing stimuli-responsive drug-carrying and drug-releasing materials.     

Highly luminescent zinc(II)-bis(8-hydroxyquinoline) complex nanorods: sonochemical synthesis, characterizations, and protein sensing

Highly luminescent zinc(II)-bis(8-hydroxyquinoline) (Znq(2)) complex nanorods have been synthesized via a sonochemical route from the microemulsion containing zinc acetate and 8-hydroxyquinoline. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the products were rod-like morphology with a diameter of about 200-450 nm and a length of about 1-3 microm. A possible mechanism for the formation of Znq(2) nanorods is proposed that the ultrasound wave might urge the collision and fusion of initial Znq(2) nuclei to form nanorods. The photoluminescence (PL) and resonance light scattering (RLS) of the products were also investigated. The Znq(2) nanorods were found to be sensitive to several proteins, such as human serum albumin (HSA), bovine serum albumin (BSA), bovine hemoglobin (Hb), and egg albumin (EA), displaying an increase in intensities of both PL and RLS. The protein-concentration dependence of the PL and RLS intensities can be well described as a Langmuir-type binding isotherm. This is the first report on the enhancement of PL and RLS intensities of Znq(2) nanorods by proteins. On the basis of enhanced PL and RLS intensities, the protein could be detected at the nanogram per milliliter level. The experimental results clearly showed that the Znq(2) nanorods were good protein probes for easy and highly sensitive detection.     

A heterometallic sandwich complex of europium(II) for luminescent studies

A divalent europium complex [(L(Ph))(2)Eu{K(THF)(2)}(2)] (L(Ph) = Ph(2)Si(NAr)(2), Ar = 2,6-(i)Pr(2)C(6)H(3)) (THF = Tetrahydrofuran) (2), which has a sandwich structure with potassium-arene π interactions, was synthesized in high yield via a one-pot process. This complex has been fully characterized, and luminescent studies showed that the 528 nm emission peak can be attributed to the 4f-5d transition of Eu(2+).     

Self-assembly of a nonanuclear nickel(II) complex and its magnetic properties

A nonanuclear nickel(II) complex [Ni9(PyA)(10)(mu3-OH)2(mu2-OH)2(mu2-OH2)2(H2O)6](ClO4)4.12H2O, containing pyridine-2-aldoximato monoanion, PyA, has been structurally and magnetochemically characterized. The nickel(II) ions, linked together via several bi- or trifurcated oximato, hydroxo, and water bridges, are antiferromagnetically coupled with the coupling constants J1 = -26.5 cm(-1) and J2 = -7.0 cm(-1), resulting in a ground state of S(t) = 1.