{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["14(14)"],"submitter":["Blasco D"],"pubmed_abstract":["Delayed fluorescence from molecules with an inverted singlet-triplet gap (DFIST) is the consequence of the unusual reverse order of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states of thermally activated delayed fluorescence (TADF) emitters. Heptazine (1,3,4,6,7,9,9<i>b</i>-heptaazaphenalene) derivatives have an inverted singlet-triplet gap thanks to the combination of multiple resonance (MR) effects and a significant double excitation character. Here, we study computationally the effect of gold(i) metalation and coordination on the optical properties of heptazine (molecule 4) and the phosphine-functionalized 2,5,8-tris(dimethylphosphino)heptazine derivatives (molecules 1-3). <i>Ab initio</i> calculations at the approximate second-order coupled cluster (CC2) and extended multiconfigurational quasi degenerate perturbation theory at the second order (XMC-QDPT2) levels show that molecules 1-4 have an inverted singlet-triplet gap due to the alternating spatial localization of the electron and hole of the exciton in the heptazine core. A non-vanishing one-electron spin-orbit coupling operator matrix element between T<sub>1</sub> and and a fast S<sub>1</sub> ← T<sub>1</sub> intersystem crossing rate constant (<i>k</i> <sub>ISC</sub>) calculated at the XMC-QDPT2(12,12) level of theory for molecule 4 suggest that this new family of complexes may be the first organometallic DFIST emitters reported."],"journal":["Chemical science"],"pagination":["3873-3880"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC10074427"],"repository":["biostudies-literature"],"pubmed_title":["Gold(i)-containing light-emitting molecules with an inverted singlet-triplet gap."],"pmcid":["PMC10074427"],"pubmed_authors":["Valiev RR","Nasibullin RT","Sundholm D","Blasco D"],"additional_accession":[]},"is_claimable":false,"name":"Gold(i)-containing light-emitting molecules with an inverted singlet-triplet gap.","description":"Delayed fluorescence from molecules with an inverted singlet-triplet gap (DFIST) is the consequence of the unusual reverse order of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states of thermally activated delayed fluorescence (TADF) emitters. Heptazine (1,3,4,6,7,9,9<i>b</i>-heptaazaphenalene) derivatives have an inverted singlet-triplet gap thanks to the combination of multiple resonance (MR) effects and a significant double excitation character. Here, we study computationally the effect of gold(i) metalation and coordination on the optical properties of heptazine (molecule 4) and the phosphine-functionalized 2,5,8-tris(dimethylphosphino)heptazine derivatives (molecules 1-3). <i>Ab initio</i> calculations at the approximate second-order coupled cluster (CC2) and extended multiconfigurational quasi degenerate perturbation theory at the second order (XMC-QDPT2) levels show that molecules 1-4 have an inverted singlet-triplet gap due to the alternating spatial localization of the electron and hole of the exciton in the heptazine core. A non-vanishing one-electron spin-orbit coupling operator matrix element between T<sub>1</sub> and and a fast S<sub>1</sub> ← T<sub>1</sub> intersystem crossing rate constant (<i>k</i> <sub>ISC</sub>) calculated at the XMC-QDPT2(12,12) level of theory for molecule 4 suggest that this new family of complexes may be the first organometallic DFIST emitters reported.","dates":{"release":"2023-01-01T00:00:00Z","publication":"2023 Apr","modification":"2025-04-19T17:28:18.288Z","creation":"2025-04-19T17:28:18.288Z"},"accession":"S-EPMC10074427","cross_references":{"pubmed":["37035700"],"doi":["10.1039/d3sc00345k"]}}