The First Synthesis of Stilbene Dendrimers and their Photochemical trans–cis Isomerization

Abstract

Highly branched stilbene dendrimers underwent trans–cis isomerization in the excited singlet state within the lifetime of 10 ns.

Stilbene Photoisomerization

“…From the time-resolved studies on energy and molecular volumes changes, it was found that the conformational change upon the trans-to cis-isomerization completed with the decay of the T 1 state for G0-G2. Photoisomerization in a series of stilbene dendrimers exhibiting fluorescence emission with considerably high quantum efficiencies was studied [107]. As shown in Ref.…”

Stilbene-cored poly(glutamate) dendrimers

“…In this area, the photoisomerization of dendrimers with photoresponsive cores-such as stilbene, [13][14][15][16][17][18][19][20][21] azobenzene, [22][23][24][25][26][27][28][29][30][31][32][33] diarylethene, [34][35][36][37][38] intramolecularly hydrogen-bonded chromophores, [39][40][41] and photolabile chromophores 42-44 -has been extensively investigated. 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.…”

Different photochemical behavior of bis(biphenyl)ethylenes and ethenes in solution and in the solid-state: Structurally controlled Z/E-photoisomerization in the solid-state

“…Among a number of photochemical molecular transformations, the E/Z-photoisomerization of olefinic compounds is the most fundamental and important process and this photochemical reaction in the confined environments has been extensively studied [1][2][3][4][5][6][7][8][9][10][11][12] in relation to the protein-bound visual chromophore. While the photoisomerization by conventional rotation, i. e., the 180 o rotation around the double bond, is regarded to be difficult within the narrow space such as in a crystal or solid-state, the Hula-twist (HT) mechanism, a space-conserving isomerization process, was proposed by Liu et al to explain such the phenomena [13][14][15][16][17].…”

“…While the photoisomerization by conventional rotation, i. e., the 180 o rotation around the double bond, is regarded to be difficult within the narrow space such as in a crystal or solid-state, the Hula-twist (HT) mechanism, a space-conserving isomerization process, was proposed by Liu et al to explain such the phenomena [13][14][15][16][17]. Not only this hypothesis has sometimes been applied to the numerous examples of E/Z-photoisomerizations in the confined environments [7,[9][10][11][12], but also several investigations have been undertaken to verify this process [18][19][20][21][22]. However, only the 1,2-disubstituted ethylenes were employed in almost all examples previously reported, but, to the best of our knowledge, the tri-and tetra-substituted alkenes have not been used for this type of investigation.…”