A visible-light and temperature responsive host–guest system: the photoisomerization and inclusion complex formation of a ruthenium complex with cyclodextrins

Abstract

In the present study, we investigated the visible-light- and thermal-stimuli-responsive properties of a host–guest system based on proximal- and distal-[Ru(C10tpy)(C10pyqu)OH2]2+ (proximal and distal-1, C10tpy = 4’-decyloxy-2,2’;6’,2”-terpyridine, C10pyqu = 2-[2’-(6’-decyloxy)-pyridyl]quinoline). The...

Binding of Stimuli-Responsive Ruthenium Aqua Complexes with 9-Ethylguanine

“…As reported previously, proximal - 1 photoisomerizes to distal - 1 to yield a mixture of the two isomers in the photostationary state. Furthermore, 1 H NMR measurements have shown that distal - 1 undergoes thermal back-isomerization to proximal - 1 at ambient temperature. , Absorption spectra during the thermal back-reaction using an aqueous solution of proximal - 1 and distal - 1 in the photostationary state are shown in Figure S6. The observed rate constant for spectral changes is 3.96 ± 0.03× 10 –5 s –1 , which is near-identical to the value obtained from 1 H NMR spectroscopy (4.0 × 10 –5 s –1 ) at the same temperature (303 K).…”

“…Ruthenium complexes with polypyridyl ligands are promising candidates for the stimuli-responsive molecules. – These complexes absorb visible light because of the metal-to-ligand charge-transfer (MLCT) transition, followed by fast relaxation of singlet excited states to triplet MLCT ( 3 MLCT) states via a radiationless intersystem crossing . The 3 MLCT excited states, which have submicrosecond lifetimes, have enabled applications in photoredox reactions, , artificial photosynthesis, – and electrochemiluminescence .…”

“…We have studied photoresponsive ruthenium aqua complexes with tridentate and asymmetric bidentate ligands. – The introduction of a substituent near the metal center enhances the quantum yields of photoisomerization and allows thermal back isomerization from the distal to proximal isomer . We have reported applications of these stimuli-responsive complexes to artificial photosynthesis, – stimulus-responsive giant vesicles, host–guest systems …”

“…44 We have reported applications of these stimuliresponsive complexes to artificial photosynthesis, 45−47 stimulus-responsive giant vesicles, 48 host−guest systems. 13 In this work, we focused on the ruthenium complex, proximal-[Ru(C 10 tpy)(C 10 pyqu) OH 2 ] 2+ (proximal-1), that responds to light and thermal stimuli (C 10 tpy = 4′-decyloxy-2,2′:6′,2″-terpyridine and C 10 pyqu = 2-[2′-(6′-decyloxy)pyridyl]quinoline). The complex absorbed visible light and photoisomerized to distal-1 (Scheme 1) 49 and thermal backisomerized to proximal-1.…”

“… 44 We have reported applications of these stimuli-responsive complexes to artificial photosynthesis, 45 – 47 stimulus-responsive giant vesicles, 48 host–guest systems. 13 …”