Efficient light harvesting and energy transfer in organic-inorganic hybrid multichromophoric materials

Thin films of silica hybrid materials consisting of two to three covalently bound organic chromophores at different ratios were conveniently synthesized and fabricated. The photophysical properties of these materials have been studied. The fluorescence spectra reveal complete fluorescence resonance energy transfer (FRET) from donor to acceptor, and the light-harvesting ability of these hybrid materials increases with increasing the molar fraction of donor chromophore. In a three-chromophore system, the energy is transferred from 300 to 530 nm successfully. Time-resolved fluorescence experiments are employed to elucidate the average rates and efficiencies (84-97%) of energy transfer in these organic/inorganic hybrid systems. The hybrid materials have been shown to provide antenna effect to facilitate energy transfer and light harvesting.     

Combining furan annulation,heck reaction,and Sonogashira coupling for the synthesis of oligoaryls

[structure: see text] A variety of benzene-furan-alkene/alkyne conjugated oligomers of precise length and constitution were synthesized iteratively by combining furan annulation, Heck reaction, and Sonogashira coupling.     

Transition metal promoted reactions : IV. Thermolysis of cyclopentadienone dimers and related compounds with group VI metal carbonyl

Thermal decomposition of dicyclopentadienone in the presence of M(CO)₆ (M = Cr, Mo, W) yields indanone. 2-Bromocyclopentadienone dimer, on the other hand, affords 4-bromoindanone under the same conditions. Nocorresponding organometallic complexes were isolated. The mechanismof this reaction is discussed.     

Furan-containing oligoaryl cyclophanene

[structure: see text] Furan-containing oligoaryl cyclophanene 1 and the corresponding cyclophane 2 were synthesized from propargylic dithioacetal 3. The electrochemical and photophysical properties and the fluxional behavior of these molecules have been examined. The emission of 1 appeared at 499 nm whereas that of 2 appeared at 389 nm.     

Synthesis and photophysical studies of siloxane-tethered cyclophanes

Novel siloxane tethered para divinylarene cyclophanes, containing phenyl, biphenyl and naphthalene rings as the aromatic nuclei, were prepared by the hydrolytic condensation of the corresponding bis{[dimethyl(i-propoxy)silyl]vinyl}arenes under basic conditions.The photophysics of the cyclophanes were investigated using UV and fluorescence spectroscopy.     

Double-stranded ladderphanes with C2-symmetric planar chiral ferrocene linkers

Eight ladderphanes with C₂-symmetric planar chiral ferrocene linkers are synthesized by ring opening metathesis polymerization of bisnorbornene monomers using Grubbs-I catalyst. The aminobenzoate in both monomers and polymers shows absorption maximum around 320 nm. Both monomers and polymers are Circular dichroism (CD) active. Little enhancements of CD profiles around 320 nm are observed for ladderphanes having chiral chloro- or phenyl-substituted ferrocene linkers. However, ladderphanes with a phenyl substituent on the cyclopendienyl ring exhibits enhancement of CD curves aound 240–300 nm. The congested phenyl moieties in adjacent linkers in this polymer might be well oriented such that interactions between these aromatic substituents on different monomeric units might provoke the enhancement of the CD curves in this region. When the methyl-substituted cyclopendienyl ligand is used for chiral ferrocene linkers, the ladderphanes exhibit two-fold enhancement of CD spectrum around 320 nm. This enhancement is further increased when the cyclopentadienyl ligand contains an additional phenyl substituent, owing to exciton coupling between aminobenzoate moieties in adjacent monomeric units. Moreover, the intensity of the CD curves in the region of 240–300 nm is significantly increased. These results suggest that the later polymer may adopt a posible helical structure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2999–3010     

A Convenient One-Pot Synthsis of Substituted Furans from Propargylic Dithioacetal

The reactions of propargylic dithioactals with organocuprate reagent have recently been explored from our laboratory.¹ In this paper, we report the reactions of propargylic dithioactals 1 with organocuprate reagents followed by treatment with an aldehyde to afford the corresponding substituted furans 2.     

Ring opening metathesis polymerization of bisnorbornene derivatives linked by Cp2Ni2(μ-S)2 bridge

ROMP of 2 with Grubbs I catalyst in CH₂Cl₂ furnished the corresponding polymer 5 which was characterized by spectroscopic means, particularly, MAS ¹³NMR. The EXAFS of 5 results were compared with those of the monomeric starting material 2 and the X-ray data of 2.