Water-soluble stilbene dendrimers

Abstract

The third generation of novel photo-responsive water-soluble stilbene dendrimer (trans- and cis-G3 WSD) undergoes unusual one-way trans-to-cis isomerization to give 100% of cis isomer at the photostationary state on UV irradiation in water.

Photochemical and complexation studies for new fluorescent and colored chelator

“…7). Water-soluble dendrimers with photoresponsive core have already been studied [61][62][63][64][65][66]. It was found that the poly aryl(ether) dendron with carboxylate anion at the periphery can produce a hydrophobic interior in aqueous solution (Fig.…”

Stilbene-cored poly(glutamate) dendrimers

“…We recently reported that stilbene dendrimers with benzyl ether-type dendrons exhibited a volume-conserving isomerization mechanism and a macromolecular effect (or generation effect) on energy transfer efficiency from the peripheral dendrons to the core stilbene in organic solvents [45][46][47] and aqueous solution. [48][49][50] In these cases, the core stilbene unit played an important role as a photo-trigger for large conformational changes (photoisomerization), and as a fluorescent probe for detecting the environment inside the dendrimer. The latter function is based on the high sensitivity to solvent polarity of the 3,3 0 ,5,5 0 -tetrasubstituted stilbene moiety of which the excited singlet state has a charge transfer (CT) character.…”

Photoisomerization and Fluorescence Characteristics of Tetramethoxystilbene in Ionic Liquid

“…Particularly, for water-soluble stilbene dendrimers we could afford nanoscale unimolecular compounds which have hydrophobic interior and hydrophilic exterior and found several unprecedented photochemical reactions such as highly selective almost one-way trans-to-cis photoisomerization in water. 6 Aromatic C=C compound with hydrogen bonding also exerted interesting photochemical properties showing one-way trans-to-cis isomerization induced by ultrafast intramolecular hydrogen atom transfer in the excited state. 7 As another approach to functionalizing molecules with C=C double bonds we are interested in introducing potentially ionic salts in photoresponsive compounds such as stilbene.…”

“…The decrease in quantum yield of trans-to-cis isomerization may have some relation to the polarity and microviscosity. However, despite the high viscosity of 260 cP for [bmim][PF 6 ] compared to that of acetonitrile (0.34 cP), the quantum yield of photoisomerization of trans-TMST seems to be considerably high indicating a nonuniform structure of ionic liquid [bmim] [PF 6 ]. In other word, there is a possibility that viscosity at microlevel seems to be lower than that of bulk state and the ionic liquid [bmim][PF 6 ] molecules should make several different environments.…”

“…15 It should be noted here that the observed lifetime of 23 ns is the longest one in simply substituted stilbenes. 6 ] are ascribable to the existence of two different solvation environments as shown in Figure 6. One of the possible environments is a nonpolar environment like benzene by agglomerating some alkyl chains and the other should be highly polar environments like ion pairs of [bmim][PF 6 ] ( Figure 6).…”