TY - JOUR

T1 - Carbazole/fluorene substituted 5-phenyl-2,2'-bipyridine D-π-A fluorophores: Photophysical data, hyperpolarizability and CT-indices

AU - Starnovskaya, Ekaterina S.

AU - Valieva, Maria I.

AU - Rammohan, Aluru

AU - Kopchuk, Dmitry S

AU - Khasanov, Albert F

AU - Taniya, Olga S

AU - Novikov, Alexander S.

AU - Kalinichev, Alexey

AU - Santra, Sougata

AU - Zyryanov, Grigory V

AU - Ranu, Brindaban

PY - 2023

Y1 - 2023

N2 - Push-pull fluorophores exhibiting pronounced intramolecular charge transfer have a low fluorescence quantum yield. Here we report a new series of D-π-A push-pull fluorophores containing a unified 2,2'-bipyridine domain acceptor with terminal electron donating carbazole/fluorene groups that exhibit good fluorescence performance. All fluorophores demonstrated high fluorescence quantum yields up to 0.99 and large Stokes shifts up to 10394 cm−1 (157 nm). For the first time, the solvatochromic method was successfully applied to 2,2'-bipyridine compounds of this type to evaluate their static and dynamic hyperpolarizability coefficients. Due to their remarkable fluorescence capability, two-photon emission cross sections were measured for three dyes using the two-photon fluorescence method. Both experimental studies and calculated charge transfer indices (CT-indices) confirmed the greatest charge separation in carbazole substituted isomers. The annelation of cyclopentene moiety to the 2,2'-bipyridine core inhibited the formation of aggregates in the solid state and significantly increased the energy gap. Finally, planarized ICT (PLICT) process was confirmed for fluorene-containing fluorophores based on theoretical calculations in the ground and excited states in various solvents. The synthesized carbazole-containing 2,2’-bipyridines are very promising ligands for constructing metallic NLO-phores, while fluorene-based fluorophores with a predominant PLICT state can be considered as promising environment polarity sensitive fluorescent dyes and biological probes to detect structural changes in proteins/biomolecular interactions and optical switches.

AB - Push-pull fluorophores exhibiting pronounced intramolecular charge transfer have a low fluorescence quantum yield. Here we report a new series of D-π-A push-pull fluorophores containing a unified 2,2'-bipyridine domain acceptor with terminal electron donating carbazole/fluorene groups that exhibit good fluorescence performance. All fluorophores demonstrated high fluorescence quantum yields up to 0.99 and large Stokes shifts up to 10394 cm−1 (157 nm). For the first time, the solvatochromic method was successfully applied to 2,2'-bipyridine compounds of this type to evaluate their static and dynamic hyperpolarizability coefficients. Due to their remarkable fluorescence capability, two-photon emission cross sections were measured for three dyes using the two-photon fluorescence method. Both experimental studies and calculated charge transfer indices (CT-indices) confirmed the greatest charge separation in carbazole substituted isomers. The annelation of cyclopentene moiety to the 2,2'-bipyridine core inhibited the formation of aggregates in the solid state and significantly increased the energy gap. Finally, planarized ICT (PLICT) process was confirmed for fluorene-containing fluorophores based on theoretical calculations in the ground and excited states in various solvents. The synthesized carbazole-containing 2,2’-bipyridines are very promising ligands for constructing metallic NLO-phores, while fluorene-based fluorophores with a predominant PLICT state can be considered as promising environment polarity sensitive fluorescent dyes and biological probes to detect structural changes in proteins/biomolecular interactions and optical switches.

UR - https://www.mendeley.com/catalogue/8672404d-2b42-3d71-b4dd-ad75f2e9a26a/

U2 - 10.1039/d3nj00394a

DO - 10.1039/d3nj00394a

M3 - Article

VL - 47

SP - 12393

EP - 12402

JO - New Journal of Chemistry

JF - New Journal of Chemistry

SN - 1144-0546

IS - 26

ER -