Excited state intramolecular double-proton transfer dynamics of [2,2′-bipyridyl]-3,3′-diol inside mesoporous silica nanochannels

• DOI: 10.1016/j.chphi.2023.100285
• Publication Date: 2023-08-12T22:46:56Z
• Authors: Joy Chatterjee; Raj Kumar Koninti; Prakash Panwaria; Partha Hazra
• Keywords: Silanol; Nanopore

The modulation of kinetics and pathways in the ESIPT process proton transfer probes holds significant potential for advancing applications bio-imaging, drug delivery, OLEDs. One effective approach achieving this is altering H-bonding donating capability surrounding medium. To investigate this, we conducted a comprehensive study on excited state intramolecular double [2,2′-bipyridyl]-3,3′-diol (BP(OH)2) within confined spaces silica nanochannels, namely, MCM-41. MCM-41, known its versatile properties, has emerged as promising host various fields, such delivery heterogeneous catalysis. Upon encapsulation BP(OH)2 significantly modulated, which reflected both steady-state time-resolved photophysical experiments. We have observed an almost 100 times increment emission intensity 30 nm blue-shift maxima when probe gets encapsulated inside nanopores. Most importantly, femtosecond up-conversion profile exhibits interesting feature. rise component 10 ps, was attributed to MK→DK conversion bulk acetonitrile (MeCN), not resides suggesting concerted rather than sequential, like case MeCN. This anomalous mechanism nanochannel weak ability silanol groups, could stabilize MK form, thus favoured pathway over sequential. Moreover, DFT calculations corroborate MCM-41 with gas-phase sequential MeCN solution-phase calculations.