TY - JOUR

T1 - Molecular Environment Effects That Modulate the Photophysical Properties of Novel 1,3-Phosphinoamines Based on 2,1,3-Benzothiadiazole

AU - Khisamov, Radmir M.

AU - Ryadun, Alexey A.

AU - Konchenko, Sergey N.

AU - Sukhikh, Taisiya S.

N1 - Funding Information: Funding: This research was funded by the Russian Science Foundation (project no. 21-73-10096). Powder XRD and luminescence kinetics studies were supported by the Ministry of Science and Higher Education of the Russian Federation (No. 121031700313-8 and No. 121031700321-3). Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022/6/1

Y1 - 2022/6/1

N2 - We report synthesis, crystal structure, and photophysical properties of novel 1,3-phosphinoamines based on 4-amino-2,1,3-benzothiadiazole (NH2-btd): Ph2 PCH(Ph)NH-btd (1) and Ph2 P(E)CH(Ph)NH-btd, (E = O (2α and 2β·thf), S (3), Se (4)). Chalcogenides 2–4 exhibit bright emissions with a major band at 519–536 nm and a minor band at 840 nm. According to TD-DFT calculations, the first band is attributed to fluorescence, while the second band corresponds to phos-phorescence. In the solid state, room temperature quantum yield reaches 93% in the case of the sulphide. The compounds under study feature effects of the molecular environment on the luminescent properties, which manifest themselves in fluorosolvatochromism as well as in a luminescent response to changes in crystal packing and in contributions to aggregation effects. Specifically, trans-formation of solid 2β·thf to solvate-free 2β either by aging or by grinding causes crystal packing changes, and, as a result, a hypsochromic shift of the emission band. Polystyrene films doped with 2 reveal a bathochromic shift upon increasing the mass fraction from 0.2 to 3.3%, which is caused by molecular aggregation effects.

AB - We report synthesis, crystal structure, and photophysical properties of novel 1,3-phosphinoamines based on 4-amino-2,1,3-benzothiadiazole (NH2-btd): Ph2 PCH(Ph)NH-btd (1) and Ph2 P(E)CH(Ph)NH-btd, (E = O (2α and 2β·thf), S (3), Se (4)). Chalcogenides 2–4 exhibit bright emissions with a major band at 519–536 nm and a minor band at 840 nm. According to TD-DFT calculations, the first band is attributed to fluorescence, while the second band corresponds to phos-phorescence. In the solid state, room temperature quantum yield reaches 93% in the case of the sulphide. The compounds under study feature effects of the molecular environment on the luminescent properties, which manifest themselves in fluorosolvatochromism as well as in a luminescent response to changes in crystal packing and in contributions to aggregation effects. Specifically, trans-formation of solid 2β·thf to solvate-free 2β either by aging or by grinding causes crystal packing changes, and, as a result, a hypsochromic shift of the emission band. Polystyrene films doped with 2 reveal a bathochromic shift upon increasing the mass fraction from 0.2 to 3.3%, which is caused by molecular aggregation effects.

KW - aggregation effects

KW - benzothiadiazole

KW - luminescence

KW - phosphinoamine

KW - single crystal X-ray diffraction

KW - TD-DFT calculations

KW - Luminescence

KW - Thiadiazoles/chemistry

UR - http://www.scopus.com/inward/record.url?scp=85132586787&partnerID=8YFLogxK

U2 - 10.3390/molecules27123857

DO - 10.3390/molecules27123857

M3 - Article

C2 - 35744980

AN - SCOPUS:85132586787

VL - 27

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 12

M1 - 3857

ER -