Abstract
The nature of carbene-metal-amide (CMA) photoluminescence in the solid state is explored through spectroscopic and quantum-chemical investigations on a representative Au-centered molecule. The crystalline phase offers well-defined coplanar geometries-enabling the link between molecular conformations and photophysical properties to be unravelled. We show that a combination of restricted torsional distortion and molecular electronic polarization blue shift the charge-transfer emission by around 400 meV in the crystalline versus the amorphous phase, through energetically raising the less-dipolar S1 state relative to S0. This blue shift brings the lowest charge-transfer states very close to the localized carbazole triplet state, whose structured emission is observable at low temperature in the polycrystalline phase. Moreover, we discover that the rate of intersystem crossing and emission kinetics are unaffected by the extent of torsional distortion. We conclude that more coplanar triplet equilibrium conformations control the photophysics of CMAs.
Original language | English |
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Pages (from-to) | 4743-4753 |
Number of pages | 11 |
Journal | Chemistry of Materials |
Volume | 32 |
Issue number | 11 |
DOIs | |
Publication status | Published - 9 Jun 2020 |
Funding
The authors thank Prof. Anna Ko\u0308hler and Prof. Heinz Ba\u0308ssler for fruitful discussions. J.F. acknowledges his parents for Ph.D financial support. E.J.T. acknowledges support from the Belgian American Educational Foundation. D.C. acknowledges support from the Royal Society (Grant No. UF130278). A.-P.M.R. acknowledges support from the Royal Society (Grant No. RGF\\EA\\180041) and the Osk, Huttunen fund. M.B. acknowledges the ERC Advanced Investigator Award (Grant No. 338944-GOCAT). A.S.R. acknowledges support from the Royal Society (Grant No. URF\\R1\\180288 and RGF\\EA\\181008). This work was supported by the EPSRC Cambridge NanoDTC, EP/L015978/1. M.L. acknowledges the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN), decision 320166. (TD)DFT computations were made possible by use of the Finnish Grid and Cloud Infrastructure resources (urn:nbn:fi:research-infras-2016072533). Research in Mons is supported by FNRS-FRFC and Consortium des Equipements de Calcul Intensif (CECI). D.B. is the FNRS research director. The work in Mons was supported by the European Commission/Re\u0301gion Wallonne (FEDER \u2013 BIORGEL project), the Consortium des E\u0301quipements de Calcul Intensif (CE\u0301CI), funded by the Fonds National de la Recherche Scientifique (F.R.S.-FNRS) under Grant No. 2.5020.11 as well as the Tier-1 supercomputer of the Fe\u0301de\u0301ration Wallonie-Bruxelles, infrastructure funded by the Walloon Region under Grant Agreement n1117545 and FRS-FNRS.
Funders | Funder number |
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FNRS‐FRFC | |
European Commission/Région Wallonne | |
Consortium des Equipements de Calcul Intensif | |
Belgian American Educational Foundation | |
European Commission | |
Fédération Wallonie-Bruxelles | |
European Regional Development Fund | |
Fonds De La Recherche Scientifique - FNRS | 2.5020.11 |
Engineering and Physical Sciences Research Council | EP/L015978/1 |
European Research Council | 338944, URF\R1\180288, RGF\EA\181008 |
Walloon Region | n1117545 |
Royal Society | RGF\EA\180041, UF130278 |
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