Vibronic relaxation dynamics at intermediate state of two-pump excitation: Photoisomerization of indocyanine green in ethanol

Investigating the role of human serum albumin protein pocket on the excited state dynamics of indocyanine green using shaped femtosecond laser pulses

“…Several single and multi-photon photoisomerization pathways have been proposed to address the nonradiative behavior of ICG. [34][35][36] They can be summarized as excited state trans-cis isomerization, triplet state formation through intersystem crossing and formation of photo degradation products. ICG cis photo-isomer and triplet state have a lifetime of B1 ms, 34 and thus can accumulate and be observed when the pulse repetition rate is 1 kHz, because consecutive pulses arrive at the sample every 1 ms. We confirmed the presence of triplet state by removing O 2 , which acts as a triplet state quencher, from the sample by bubbling argon (Ar) in the solution and recording the chirp scans in the oxygen depleted samples.…”

“…[24][25][26][27][28][29] The spectroscopic properties of ICG have already been well investigated [30][31][32][33] and several photoisomerization mechanisms were sought for ICG that address multiphoton processes to produce triplet state, photodegraded species and cis isomers. [34][35][36] Being a tricarbocyanine dye, ICG aggregation and photophysical behavior is highly dependent on the environment 31 and the molecule tends to exist in an all-trans form while in the ground state. 34,35 Moreover, the low fluorescence quantum yield for ICG in water (f F = 0.027) 31 can be attributed to the excited state trans-cis isomerization, 37,38 large triplet state formation cross section 32 and several other photoreactions.…”

“…34,35 Moreover, the low fluorescence quantum yield for ICG in water (f F = 0.027) 31 can be attributed to the excited state trans-cis isomerization, 37,38 large triplet state formation cross section 32 and several other photoreactions. [34][35][36] The main medical use of ICG arises from its ability to bind with albumin 39,40 and is therefore extensively used in the labeling of HSA. 41,42 ICG has a binding constant of 5.7 Â 10 5 M À1 to HSA 43 and results in a bathochromic shift (red shift) of the ICG absorbance (ESI †, Fig.…”

One-Dimensionally Conjugated Carbocyanine Dyes Isolated under Cold Gas-Phase Conditions: Electronic Spectra and Photochemistry

“…The isomerization pathway in the S 1 state is barrierless for these dyes, in sharp contrast to the activation barriers for photoisomerization confirmed for longer-chain cyanine dyes, such as 1 (Scheme ) and 1,1′-diethyl-2,2′-dicarbocyanine (DDI) . It is also significant that these dye molecules, in general, have a large cross section for multiphoton absorption, which often plays a key role in their photoisomerization, as revealed for 2 (Scheme ) and related molecules. ,, The excited-state dynamics described beforehand should be reflected in the spectral profiles; therefore, reliable electronic spectra of these molecules are highly desired.…”

“…Other characteristic aspects of these molecules include their photochemistry. The trans – cis photoisomerization in their conjugated chains has been of significant research interest, − in relation to well-known molecules, such as stilbene, rhodopsins, and photoactive yellow proteins (PYPs) . Our recent studies also include investigations on the mechanisms of trans – cis photoisomerization, in particular, those of cinnamic acid derivatives. − Regarding cyanine dyes, the photoisomerization processes of short-chain molecules, such as 1,1′-diethyl-2,2′-cyanine (1122C) and 1,1′-diethyl-4,4′-cyanine (1144C), have been extensively studied in solution; − the internal rotations of the conjugated chains in the electronically excited S 1 state, which is correlated to isomerization, have been probed using a variety of ultrafast spectroscopic techniques.…”