The magnitude of the reorganization energy is closely related to the nonradiative relaxation rate, which affects the photoemission quantum efficiency, particularly for the emission with a lower energy gap toward the near IR (NIR) region. In this study, we explore the relationship between the reorganization energy and the molecular geometry, and hence the transition density by computational methods using two popular models of NIR luminescent materials: (1) linearly conjugated cyanine dyes and (2) electron donor-acceptor (D-A) composites with various degrees of charge transfer (CT) character. We find that in some cases, reorganization energies can be significantly reduced to 50% despite slight structural modifications. Detailed analyses indicate that the reflection symmetry plays an important role in linear cyanine systems. As for electron donor-acceptor systems, both the donor strength and the substitution position affect the relative magnitude of reorganization energies. If CT is dominant and creates large spatial separation between HOMO and LUMO density distributions, the reorganization energy is effectively increased due to the large electron density variation between S and S states. Mixing a certain degree of local excitation (LE) with CT in the S state reduces the reorganization energy. The principles proposed in this study are also translated into various pathways of canonically equivalent π-conjugation resonances to represent intramolecular π-delocalization, the concept of which may be applicable, in a facile manner, to improve the emission efficiency especially in the NIR region.
Chem Rev. 1996 May 9;96(3):911-926
[PMID:
11848775]
Chem Soc Rev. 2010 Feb;39(2):423-34
[PMID:
20111768]
Chemistry. 2009 Jul 20;15(29):7225-37
[PMID:
19544517]
Angew Chem Int Ed Engl. 2021 Jan 11;60(2):800-805
[PMID:
32918358]
J Phys Chem A. 2005 Jun 2;109(21):4804-15
[PMID:
16833824]
J Am Chem Soc. 2012 Jan 18;134(2):1200-11
[PMID:
22176300]
Inorg Chem. 1996 Apr 10;35(8):2242-2246
[PMID:
11666419]
J Am Chem Soc. 2021 May 12;143(18):6836-6846
[PMID:
33939921]
J Am Chem Soc. 2018 Feb 7;140(5):1715-1724
[PMID:
29337545]
Chem Soc Rev. 2013 Apr 21;42(8):3453-88
[PMID:
23396530]
J Am Chem Soc. 2005 Feb 23;127(7):2339-50
[PMID:
15713114]
J Chem Phys. 2004 Dec 22;121(24):12613-7
[PMID:
15606285]
Astrophys J. 1996 Feb 20;458(2 Pt 1):621-36
[PMID:
11538558]
Nat Commun. 2015 Dec 02;6:10085
[PMID:
26626042]
Nanomedicine. 2017 Apr;13(3):955-963
[PMID:
27884637]
Phys Chem Chem Phys. 2008 Nov 28;10(44):6615-20
[PMID:
18989472]
Angew Chem Int Ed Engl. 2002 Jul 2;41(13):2344-7
[PMID:
12203587]
J Am Chem Soc. 2002 Jul 10;124(27):7918-9
[PMID:
12095333]
Bioconjug Chem. 2002 May-Jun;13(3):605-10
[PMID:
12009952]
J Phys Chem Lett. 2020 Jun 18;11(12):4548-4553
[PMID:
32437617]
Nat Commun. 2020 Apr 21;11(1):1925
[PMID:
32317631]
Phys Chem Chem Phys. 2020 Jul 21;22(27):15496-15508
[PMID:
32602504]
Nat Commun. 2020 Mar 9;11(1):1255
[PMID:
32152288]
J Med Chem. 2019 Feb 28;62(4):2049-2059
[PMID:
30501190]
J Phys Chem A. 2020 Sep 24;124(38):7644-7657
[PMID:
32864966]
J Org Chem. 2007 Dec 7;72(25):9550-6
[PMID:
17979286]
J Phys Chem A. 2020 Nov 12;124(45):9478-9486
[PMID:
33141580]
Chemistry. 2008;14(22):6734-41
[PMID:
18551687]
Adv Mater. 2011 Mar 4;23(9):1137-44
[PMID:
21360769]
Angew Chem Int Ed Engl. 2022 Jun 13;61(24):e202117436
[PMID:
35294084]
Phys Chem Chem Phys. 2020 Oct 7;22(38):21630-21641
[PMID:
32969457]
J Phys Chem A. 2013 Aug 22;117(33):8017-25
[PMID:
23895675]
Biomed Mater. 2013 Feb;8(1):014110
[PMID:
23353894]
J Phys Chem A. 2011 Dec 22;115(50):14519-25
[PMID:
22060634]
Chemphyschem. 2006 Sep 11;7(9):2003-7
[PMID:
16952119]
Phys Rev A Gen Phys. 1988 Sep 15;38(6):3098-3100
[PMID:
9900728]
Nat Nanotechnol. 2018 May;13(5):376-380
[PMID:
29662243]
Angew Chem Int Ed Engl. 2021 Jan 11;60(2):983-989
[PMID:
32990356]
J Chem Phys. 2005 Jul 8;123(2):24301
[PMID:
16050739]
Chemistry. 2007;13(17):4750-8
[PMID:
17373008]
Polymers (Basel). 2017 Dec 27;10(1):
[PMID:
30966065]
Chem Rev. 2005 Aug;105(8):2999-3093
[PMID:
16092826]
J Am Chem Soc. 2009 Jul 1;131(25):8787-97
[PMID:
19505071]
Chem Rev. 2004 Nov;104(11):4971-5004
[PMID:
15535639]
Phys Chem Chem Phys. 2021 Mar 11;23(9):5652-5664
[PMID:
33656501]
Acc Chem Res. 2016 Sep 20;49(9):1731-40
[PMID:
27564418]
