Transient Glass Formation around a Quadrupolar Photoexcited Dye in a Strongly H‐Bonding Liquid Observed by Transient 2D‐IR Spectroscopy

Abstract

Intermolecular H-bonding dynamics around aphotoexcited quadrupolar dye is directly observed using transient 2D-IR spectroscopy. Upon solvent-induced symmetry breaking, the H-bond accepting abilities of the two nitrile end-groups change drastically,a nd in extremely protic (superprotic) solvents,atight H-bond complex forms at one end. The time evolution of the 2D C Nlineshape in methanol points to rapid, 2-3 ps,spectral diffusion due to fluctuations of the H-bonding network. Similar behavior is observed in asuperprotic solvent shortly after photoexcitation of the dye.However,atlater times, the completely inhomogeneous band does not exhibit spectral diffusion for at least 5ps, pointing to aglass-like environment around one side of the dye.About half of the excited dyes show this behavior attributed to the tight H-bond complex, whereas the others are loosely bound. Aw eak cross peak indicates partial exchange between these excited state subpopulations.

Excited-state symmetry breaking in 9,10-dicyanoanthracene-based quadrupolar molecules: the effect of donor–acceptor branch length

“…Whereas TRIR measurements proved to be the workhorse for monitoring ES-SB dynamics, [16][17][18][19]25,30,40,41 electronic transient absorption (TA) spectroscopy was less successful. However, we recently demonstrated that ES-SB can be visualised by monitoring the appearance of excited-state absorption (ESA) bands that are Laporte forbidden in the symmetric quadrupolar state.…”

“…Control on the extent of ES-SB can be achieved by tuning the properties of the local environment of the molecule with solvents of different polarity and H-bonding ability, [16][17][18][19][20]25,41 as well as the strength of D and A subunits. 30 The latter property is directly linked to the change of quadrupole moment upon excitation, which is also an important tuning parameter for ES-SB.…”

Влияние Асимметричного Переноса Зарядана ИК Спектры Возбужденных Квадрупольных Молекул

“…Это означает, что параметр малости в разложении по степеням параметра асимметрии (3) имеет порядок 0.01, что гарантирует высокую точность используемого приближения. Этот малый параметр позволяет также пренебречь влиянием квадратичного электронноколебательное взаимодействие U ИК полос, измеренных методами нестационарной 2D ИК спектроскопии [21]. Они приблизительно равны η s ∼ = η a = 10 cm −1 .…”

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

“…Sedangkan klorin memiliki nomor atom 17, untuk stabil klorin menangkap 1 elektron dari atom lain. sehingga, jika natrium dengan klor berikatan, akan terjadi serah terima elektron yang menyebabkan mereka berikatan (49)(50)(51)(52) ionik. Ada dua atom penyusun NaCl yaitu natrium dan klor.…”