Deciphering Charge-Transfer and Triplet-Multiplet Excited States in Substituted MnIII and CrIII Phthalocyanines: Insights from UV-Vis-NIR, MCD, and Theory
- 1Department of Chemistry
- 2University of Tennessee
- 3Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada, V5A 1S6
Abstract
Charge-transfer (metal-to-ligand, MLCT, ligand-to-metal, LMCT, and interligand, (LLCT) and intraligand (π−π* and triplet-multiplet) transitions observed in the UV-vis-NIR and magnetic circular dichroism (MCD) spectra of high-spin Pc tBu Cr III Cl, Pc tBu Mn III Cl, and Pc OBu Mn III Cl (Pc tBu is the dianion of the 2,9(10),16(17),23(24)-tetra-tert-butyl-phthalocyanine and Pc OBu is the dianion of the 1,4,8,11,15,18,22,25-octa-n-butoxy-phthalocyanine) complexes were analyzed with the help of group theory combined with time-dependent density functional theory and ab initio (CASSCF and NEVPT2(13e,14o)) calculations. The energy shift between tert-butylated and butoxylated Pc rings, the energy shift between Mn and Cr centers, and the change in solvent donicity between dichloromethane/chloroform (DCM / CHCl 3 ) and N,N-dimethylformamide (DMF) were used to systematically perturb the energies of electronic transitions. It was demonstrated that the triplet-multiplet transitions dominate the NIR region of the UV-vis-NIR and MCD spectra, while LMCT bands dominate the “phthalocyanine window” (350-550 nm) region of the UV-vis-NIR and MCD spectra. Like other trivalent transition-metal phthalocyanines, MLCT transitions were predicted in the UV region of the UV-vis-NIR and MCD spectra. General trends in triplet-multiplet transitions across d 1 -d 9 configurations as well as the function of axial ligands for a given metal are delineated and parameterized. These studies will be used for further understanding of wavelength-dependent photochemical activity and the effects of structural substitutions on electrocatalytic and photocatalytic transformations.
Related
- Potential-Dependent Redox Speciation in Substituted MnIII and CrIII Phthalocyanines
- Deciphering Inter-Heme Electron Transfer Pathways in a Diheme Peroxidase from Methane-Oxidizing Bacteria
- Rhodium‐Catalyzed Synthesis of Enantioenriched α‐Substituted Primary Amines Through Asymmetric Transfer Hydrogenation
- Geminal Metalloid Substituents Enable Stereoselective Geometric Isomerization of Highly Substituted Alkenes via Energy-Transfer Catalysis
- Deciphering the anticorrosion performance of Arnica montana extract for mild steel in 1.5 M HCl using experimental and computational insights
BibTeX
@misc{tuggle2026deciphering,
title = {{Deciphering Charge-Transfer and Triplet-Multiplet Excited States in Substituted MnIII and CrIII Phthalocyanines: Insights from UV-Vis-NIR, MCD, and Theory}},
author = {Kelsie J. Tuggle and Haleigh M. Grace and Breanna E. Muldowney and Ryan. S. Arnold and Emma E. Lane and Daniel B. Leznoff and Konstantinos Vogiatzis and Viktor N. Nemykin and Brendon J. McNicholas},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008160/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008160/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Deciphering Charge-Transfer and Triplet-Multiplet Excited States in Substituted MnIII and CrIII Phthalocyanines: Insights from UV-Vis-NIR, MCD, and Theory
AU - Kelsie J. Tuggle
AU - Haleigh M. Grace
AU - Breanna E. Muldowney
AU - Ryan. S. Arnold
AU - Emma E. Lane
AU - Daniel B. Leznoff
AU - Konstantinos Vogiatzis
AU - Viktor N. Nemykin
AU - Brendon J. McNicholas
PY - 2026
DA - 2026/09/20
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008160/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008160/v1
AB - Charge-transfer (metal-to-ligand, MLCT, ligand-to-metal, LMCT, and interligand, (LLCT) and intraligand (π−π* and triplet-multiplet) transitions observed in the UV-vis-NIR and magnetic circular dichroism (MCD) spectra of high-spin Pc tBu Cr III Cl, Pc tBu Mn III Cl, and Pc OBu Mn III Cl (Pc tBu is the dianion of the 2,9(10),16(17),23(24)-tetra-tert-butyl-phthalocyanine and Pc OBu is the dianion of the 1,4,8,11,15,18,22,25-octa-n-butoxy-phthalocyanine) complexes were analyzed with the help of group theory combined with time-dependent density functional theory and ab initio (CASSCF and NEVPT2(13e,14o)) calculations. The energy shift between tert-butylated and butoxylated Pc rings, the energy shift between Mn and Cr centers, and the change in solvent donicity between dichloromethane/chloroform (DCM / CHCl 3 ) and N,N-dimethylformamide (DMF) were used to systematically perturb the energies of electronic transitions. It was demonstrated that the triplet-multiplet transitions dominate the NIR region of the UV-vis-NIR and MCD spectra, while LMCT bands dominate the “phthalocyanine window” (350-550 nm) region of the UV-vis-NIR and MCD spectra. Like other trivalent transition-metal phthalocyanines, MLCT transitions were predicted in the UV region of the UV-vis-NIR and MCD spectra. General trends in triplet-multiplet transitions across d 1 -d 9 configurations as well as the function of axial ligands for a given metal are delineated and parameterized. These studies will be used for further understanding of wavelength-dependent photochemical activity and the effects of structural substitutions on electrocatalytic and photocatalytic transformations.
ER -