2,6-/1,5-Naphthoquinodimethane bridged porphyrin dimer diradicaloids

Hejian Zhang, Jinseok Kim, Hoa Phan, Tun Seng Herng, Tullimilli Y. Gopalakrishna, Wangdong Zeng, Jun Ding, Dongho Kim, Jishan Wu

Research output: Contribution to journalArticle

Abstract

2,6-Naphthoquinodimethane (2,6-NQDM)- A nd 1,5-naphthoquinodimethane (1,5-NQDM)-bridged porphyrin dimers, 2,6-P2 and 1,5-P2, were synthesized as relatively stable compounds. Both exhibit open-shell singlet ground state according to variable-temperature (VT) NMR and magnetic measurements, as well as restricted active space spin-flip (RAS-SF) calculations. The 1,5-P2 isomer has a larger diradical character (y0 = 0.772, based on the RAS-SF calculations) and smaller singlet-triplet energy gap (Î"ES-T =-2.6 kcal/mol, based on SQUID measurements) compared to the 2,6-P2 isomer (y0 = 0.501, Î"ES-T =-3.1 kcal/mol). In addition, 2,6-P2 shows intense one-photon absorption (OPA) (λmax = 976 nm, = 72200 M-1â cm-1) and a large two-photon absorption (TPA) cross-section (σmax(2) = 3500 GM at 1400 nm) in the near-infrared region, while 1,5-P2 with larger diradical character displays red-shifted but weaker OPA (λmax = 1147 nm, = 18030 M-1â cm-1) and a smaller TPA cross-section (σmax(2) = 1750 GM at 1600 nm). Both compounds show four reversible redox waves and 1,5-P2 has a smaller electrochemical energy gap (1.06 eV vs.1.16 eV for 2,6-P2). Therefore, the bridge structure has a significant impact on the diradical character, electronic properties, and magnetic behaviors of the obtained porphyrin-based diradicaloids.

Original languageEnglish
JournalJournal of Porphyrins and Phthalocyanines
DOIs
Publication statusAccepted/In press - 2019 Jan 1

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Porphyrins
Dimers
Photons
Isomers
Energy gap
SQUIDs
Magnetic variables measurement
Electronic properties
Ground state
Nuclear magnetic resonance
Infrared radiation
Temperature

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

Zhang, H., Kim, J., Phan, H., Herng, T. S., Gopalakrishna, T. Y., Zeng, W., ... Wu, J. (Accepted/In press). 2,6-/1,5-Naphthoquinodimethane bridged porphyrin dimer diradicaloids. Journal of Porphyrins and Phthalocyanines. https://doi.org/10.1142/S1088424619500998
Zhang, Hejian ; Kim, Jinseok ; Phan, Hoa ; Herng, Tun Seng ; Gopalakrishna, Tullimilli Y. ; Zeng, Wangdong ; Ding, Jun ; Kim, Dongho ; Wu, Jishan. / 2,6-/1,5-Naphthoquinodimethane bridged porphyrin dimer diradicaloids. In: Journal of Porphyrins and Phthalocyanines. 2019.
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abstract = "2,6-Naphthoquinodimethane (2,6-NQDM)- A nd 1,5-naphthoquinodimethane (1,5-NQDM)-bridged porphyrin dimers, 2,6-P2 and 1,5-P2, were synthesized as relatively stable compounds. Both exhibit open-shell singlet ground state according to variable-temperature (VT) NMR and magnetic measurements, as well as restricted active space spin-flip (RAS-SF) calculations. The 1,5-P2 isomer has a larger diradical character (y0 = 0.772, based on the RAS-SF calculations) and smaller singlet-triplet energy gap ({\^I}{"}ES-T =-2.6 kcal/mol, based on SQUID measurements) compared to the 2,6-P2 isomer (y0 = 0.501, {\^I}{"}ES-T =-3.1 kcal/mol). In addition, 2,6-P2 shows intense one-photon absorption (OPA) (λmax = 976 nm, = 72200 M-1{\^a} cm-1) and a large two-photon absorption (TPA) cross-section (σmax(2) = 3500 GM at 1400 nm) in the near-infrared region, while 1,5-P2 with larger diradical character displays red-shifted but weaker OPA (λmax = 1147 nm, = 18030 M-1{\^a} cm-1) and a smaller TPA cross-section (σmax(2) = 1750 GM at 1600 nm). Both compounds show four reversible redox waves and 1,5-P2 has a smaller electrochemical energy gap (1.06 eV vs.1.16 eV for 2,6-P2). Therefore, the bridge structure has a significant impact on the diradical character, electronic properties, and magnetic behaviors of the obtained porphyrin-based diradicaloids.",
author = "Hejian Zhang and Jinseok Kim and Hoa Phan and Herng, {Tun Seng} and Gopalakrishna, {Tullimilli Y.} and Wangdong Zeng and Jun Ding and Dongho Kim and Jishan Wu",
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2,6-/1,5-Naphthoquinodimethane bridged porphyrin dimer diradicaloids. / Zhang, Hejian; Kim, Jinseok; Phan, Hoa; Herng, Tun Seng; Gopalakrishna, Tullimilli Y.; Zeng, Wangdong; Ding, Jun; Kim, Dongho; Wu, Jishan.

In: Journal of Porphyrins and Phthalocyanines, 01.01.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 2,6-/1,5-Naphthoquinodimethane bridged porphyrin dimer diradicaloids

AU - Zhang, Hejian

AU - Kim, Jinseok

AU - Phan, Hoa

AU - Herng, Tun Seng

AU - Gopalakrishna, Tullimilli Y.

AU - Zeng, Wangdong

AU - Ding, Jun

AU - Kim, Dongho

AU - Wu, Jishan

PY - 2019/1/1

Y1 - 2019/1/1

N2 - 2,6-Naphthoquinodimethane (2,6-NQDM)- A nd 1,5-naphthoquinodimethane (1,5-NQDM)-bridged porphyrin dimers, 2,6-P2 and 1,5-P2, were synthesized as relatively stable compounds. Both exhibit open-shell singlet ground state according to variable-temperature (VT) NMR and magnetic measurements, as well as restricted active space spin-flip (RAS-SF) calculations. The 1,5-P2 isomer has a larger diradical character (y0 = 0.772, based on the RAS-SF calculations) and smaller singlet-triplet energy gap (Î"ES-T =-2.6 kcal/mol, based on SQUID measurements) compared to the 2,6-P2 isomer (y0 = 0.501, Î"ES-T =-3.1 kcal/mol). In addition, 2,6-P2 shows intense one-photon absorption (OPA) (λmax = 976 nm, = 72200 M-1â cm-1) and a large two-photon absorption (TPA) cross-section (σmax(2) = 3500 GM at 1400 nm) in the near-infrared region, while 1,5-P2 with larger diradical character displays red-shifted but weaker OPA (λmax = 1147 nm, = 18030 M-1â cm-1) and a smaller TPA cross-section (σmax(2) = 1750 GM at 1600 nm). Both compounds show four reversible redox waves and 1,5-P2 has a smaller electrochemical energy gap (1.06 eV vs.1.16 eV for 2,6-P2). Therefore, the bridge structure has a significant impact on the diradical character, electronic properties, and magnetic behaviors of the obtained porphyrin-based diradicaloids.

AB - 2,6-Naphthoquinodimethane (2,6-NQDM)- A nd 1,5-naphthoquinodimethane (1,5-NQDM)-bridged porphyrin dimers, 2,6-P2 and 1,5-P2, were synthesized as relatively stable compounds. Both exhibit open-shell singlet ground state according to variable-temperature (VT) NMR and magnetic measurements, as well as restricted active space spin-flip (RAS-SF) calculations. The 1,5-P2 isomer has a larger diradical character (y0 = 0.772, based on the RAS-SF calculations) and smaller singlet-triplet energy gap (Î"ES-T =-2.6 kcal/mol, based on SQUID measurements) compared to the 2,6-P2 isomer (y0 = 0.501, Î"ES-T =-3.1 kcal/mol). In addition, 2,6-P2 shows intense one-photon absorption (OPA) (λmax = 976 nm, = 72200 M-1â cm-1) and a large two-photon absorption (TPA) cross-section (σmax(2) = 3500 GM at 1400 nm) in the near-infrared region, while 1,5-P2 with larger diradical character displays red-shifted but weaker OPA (λmax = 1147 nm, = 18030 M-1â cm-1) and a smaller TPA cross-section (σmax(2) = 1750 GM at 1600 nm). Both compounds show four reversible redox waves and 1,5-P2 has a smaller electrochemical energy gap (1.06 eV vs.1.16 eV for 2,6-P2). Therefore, the bridge structure has a significant impact on the diradical character, electronic properties, and magnetic behaviors of the obtained porphyrin-based diradicaloids.

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