title: Efficient intersystem crossing using singly halogenated carbomethoxyphenyl porphyrins measured using delayed fluorescence, chemical quenching, and singlet oxygen emission.
abstract: Sensitizers with high triplet quantum yields are useful for generating photovoltaics, photocatalysts and photodynamic therapy agents with increased efficiency. In this study, the heavy atom effect was used to optimize the triplet and singlet oxygen quantum yields of 5,10,15,20-tetrakis(4-carbomethoxyphenyl)porphyrin (1-TCM4PP). The triplet quantum yields, determined using delayed fluorescence, was calculated as 0.35 for 1-TCM4PP, 0.75 for 5,10,15-tris(4-carbomethoxyphenyl)-20-(4-bromophenyl)porphyrin (2-TBCM3PP) and 0.88 for 5,10,15-tris(4-carbomethoxyphenyl)-20-(4-iodophenyl)porphyrin (3-TCM3IPP). Chemical quenching of 1,3-diphenylisobenzofuran and singlet oxygen emission studies rendered an average singlet oxygen quantum yield of 0.51, 0.75, and 0.90 for TCM4PP, TBCM3PP and TCM3IPP respectively. These photophysical properties indicate that a single halogen atom is capable of transforming TCM4PP into a sensitizer with strong triplet character. This is useful for generating singlet oxygen for photodynamic therapy, creating a long lasting reactive species for catalysis and for extending diffusion lengths in photovoltaic applications while retaining three molecular modification points for further functionalization.
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Marin
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Sonia
authors.initials: S
authors.lastname: Payerpaj
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Graham S
authors.initials: GS
authors.lastname: Collier
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Angy L
authors.initials: AL
authors.lastname: Ortiz
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Singh
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Marcus
authors.initials: M
authors.lastname: Jones
authors.affiliation: Department of Chemistry, Burson 200, 9201 University City Blvd., Charlotte, NC 28223-0001, USA. Michael.Walter@uncc.edu.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Walter
mesh_terms: D002384:Catalysis; D054879:Halogenation; D008027:Light; D017319:Photosensitizing Agents / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D026082:Singlet Oxygen / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D026082:Singlet Oxygen