TY - JOUR

T1 - Twisted BODIPY derivative

T2 - intersystem crossing, electron spin polarization and application as a novel photodynamic therapy reagent

AU - Dong, Yu

AU - Kumar, Prashant

AU - Maity, Partha

AU - Kurganskii, Ivan

AU - Li, Shujing

AU - Elmali, Ayhan

AU - Zhao, Jianzhang

AU - Escudero, Daniel

AU - Wu, Huijian

AU - Karatay, Ahmet

AU - Mohammed, Omar F.

AU - Fedin, Matvey

N1 - Funding Information: J. Z. thanks the NSFC (U2001222, 21673031, 21761142005 and 21911530095) for financial support. M. F. thanks the Ministry of High Education and Science of Russia for access to EPR equipment. I. K. thanks RFBR (grant no. 19-29-10035) for financial support. D. E. thanks funding from KU Leuven Internal Funds. Publisher Copyright: © the Owner Societies 2021. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/4/14

Y1 - 2021/4/14

N2 - The photophysical properties of a heavy atom-free BODIPY derivative with a twisted p-conjugated framework were studied. Efficient intersystem crossing (ISC quantum yield: 56%) and an exceptionally long-lived triplet state were observed (4.5 ms in solid polymer film matrix and 197.5 µs in solution). Time-resolved electron paramagnetic resonance (TREPR) spectroscopy and DFT computations confirmed the delocalization of the triplet state on the whole twisted p-conjugated framework and the zero-field-splitting (ZFS)Dparameter ofD= -69.5 mT, which is smaller than that of 2,6-diiodoBODIPY (D= -104.6 mT). The electron spin polarization (ESP) phase pattern of the triplet state TREPR spectrum of the twisted BODIPY is (a, a, e, a, e, e), which is different from that of 2,6-diiodo BODIPY (e, e, e, a, a, a), indicating that the electron spin selectivity of the ISC of the twisted structure is different from that of the spin orbital coupling effect. According to the computed spin-orbit coupling matrix elements (0.154-1.964 cm-1), together with the matched energy of the S1/Tnstates, ISC was proposed to occurviaS1?T2/T3. The computational results were consistent with TREPR results on the electron spin selectivity (the overpopulation of the TYsublevel of the T1state). The advantage of the long-lived triplet state of the twisted BODIPY was demonstrated by its efficient singlet oxygen (1O2) photosensitizing (F?= 50.0%) even under a severe hypoxia atmosphere (pO2= 0.2%, v/v). A high light toxicity (EC50= 1.0 µM) and low dark toxicity (EC50= 78.5 µM) were observed for the twisted BODIPY, and thus the cellular studies demonstrate its potential as a novel potent heavy atom-free photodynamic therapy (PDT) agent.

AB - The photophysical properties of a heavy atom-free BODIPY derivative with a twisted p-conjugated framework were studied. Efficient intersystem crossing (ISC quantum yield: 56%) and an exceptionally long-lived triplet state were observed (4.5 ms in solid polymer film matrix and 197.5 µs in solution). Time-resolved electron paramagnetic resonance (TREPR) spectroscopy and DFT computations confirmed the delocalization of the triplet state on the whole twisted p-conjugated framework and the zero-field-splitting (ZFS)Dparameter ofD= -69.5 mT, which is smaller than that of 2,6-diiodoBODIPY (D= -104.6 mT). The electron spin polarization (ESP) phase pattern of the triplet state TREPR spectrum of the twisted BODIPY is (a, a, e, a, e, e), which is different from that of 2,6-diiodo BODIPY (e, e, e, a, a, a), indicating that the electron spin selectivity of the ISC of the twisted structure is different from that of the spin orbital coupling effect. According to the computed spin-orbit coupling matrix elements (0.154-1.964 cm-1), together with the matched energy of the S1/Tnstates, ISC was proposed to occurviaS1?T2/T3. The computational results were consistent with TREPR results on the electron spin selectivity (the overpopulation of the TYsublevel of the T1state). The advantage of the long-lived triplet state of the twisted BODIPY was demonstrated by its efficient singlet oxygen (1O2) photosensitizing (F?= 50.0%) even under a severe hypoxia atmosphere (pO2= 0.2%, v/v). A high light toxicity (EC50= 1.0 µM) and low dark toxicity (EC50= 78.5 µM) were observed for the twisted BODIPY, and thus the cellular studies demonstrate its potential as a novel potent heavy atom-free photodynamic therapy (PDT) agent.

UR - http://www.scopus.com/inward/record.url?scp=85104324220&partnerID=8YFLogxK

U2 - 10.1039/d1cp00948f

DO - 10.1039/d1cp00948f

M3 - Article

C2 - 33876025

AN - SCOPUS:85104324220

VL - 23

SP - 8641

EP - 8652

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 14

ER -