The effect of hydrophobic-lipophilic interactions on chemical reactivity. 8. Large-ring intramolecular excimer formation brought about by hydrophobic forces

New Intramolecular α-Arylation Strategy of Ketones by the Reaction of Silyl Enol Ethers to Photosensitized Electron Transfer Generated Arene Radical Cations: Construction of Benzannulated and Benzospiroannulated Compounds

“…Small amounts (>10%) of starting ketone wrtr recovered in this case too (Scheme 6). The ease observed during this cyclization may possibly be explained by considering the proximity between the arene radical cation and enol silyl ethers in aqueous medium due to self-coiling as demonstrated by Jiang et al …”

Nature of the Alternate CF2CH2 Chain: Study Based on the Measurement and Comparison of the CAgC's of Aggregators with Alternate Chains and with Hydrocarbon Chains

“…These compounds have fluorescence λ max at 337 nm (naphthalene ring) and 400 nm (excimer). The latter was used to monitor excimer formation, which gives direct evidence to aggregate formation. , It was found that in the Φ = 0.20 DX−H 2 O system the excimer peak of Fl- C- m ( m = 7, 9, 11, and 13) appears at 400 nm if their concentrations are beyond a certain value, i.e., CAgC. Similarly, excimer formation was also observed from compounds Fl- AL- m ( m = 7, 9, 11, and 13) (see Figures and ).…”

“…In recent years, CAgC has been firmly established as the most reliable indicator of the aggregating tendency of an Agr. ,, The best methods used for the evaluation of CAgC are those of plotting log k ob against the logarithm of the initial concentration of the ester ([Agr] i ), where k ob is the observed saponification rate constant of the ester Agr, as illustrated by Figures and , , and those of plotting log ( I e / I m ) or I e / I m against the concentration of the Agr-probe species ([Agr]), where I e and I m are the relative fluorescence intensities of the monomer and the excimer of the fluorescence probe, as illustrated by Figures and . ,, The two methods are therefore selected for the present study, with the target probes C- m and AL- m serving as substrates for kinetic measurements and with Fl- C- m and Fl- AL- m serving as the target probes for fluorescence measurements.

1 Plot of log k ob vs logarithm of initial concentration of C- m in the Φ = 0.20 buffered DX−H 2 O system at 35 °C.

2 Plot of log k ob vs logarithm of initial concentration of AL- m in the Φ = 0.20 buffered DX−H 2 O system at 35 °C.

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Effect of coaggregate formation on the fluorescence quenching of anthracene derivatives bym-N,N-diethyl-­aminophenyl carboxylates with different chain lengths as quenchers

“…[4][5][6] Since aggregates of electrically neutral organic molecules are formed almost solely by HLI, some recent efforts have been dedicated to studies of hydrophobic effects on photochemical and photophysical processes. [7][8][9] It has been reported that aggregation, coaggregation and self-coiling of organic molecules affect the formation of excimers, the enhancement of energy transfer between excited donors and acceptors 9,10 and the hydrophobic acceleration of electron transfer processes. 11 In the present work, a novel finding is that at low concentrations ($10 À6 M) *A-n can be used as an acceptor when P-n was used as a donor, but when S-12 was used as an acceptor, *A-12 becomes a donor in electron-transfer quenching process driven by HLI (see structures below).…”