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Turner EE, Pham TN, Smith SP, Ward KN, Rosenthal J, Rack JJ. Electron-Withdrawing meso-Substituents Turn On Magneto-Optical Activity in Porphyrins. Inorg Chem 2024; 63:3630-3636. [PMID: 38359443 DOI: 10.1021/acs.inorgchem.3c04004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
A series of square planar metalloporphyrins (M(TPP), TPP is 5,10,15,20-tetraphenylporphyrin and M(TPFPP), TPFPP is 5,10,15,20-tetrapentafluorophenylporphyrin; M is Zn2+, Ni2+, Pd2+, or Pt2+) with distinct meso-substituents were prepared, and their magneto-optical activity (MOA) was characterized by magnetic circular dichroism (MCD) and magneto-optical rotary dispersion spectroscopy (MORD; also known as Faraday rotation spectroscopy). MOA is crucial in the development of next-generation magneto-optical devices and quantum computing. The data show that the presence of meso-pentafluorophenyl substituents results in significant increase in MOA in comparison to the homologous phenyl group. Differences in the MOA of these metalloporphyrins are rationalized using the Gouterman four-orbital model and pave the way for rational design of improved and tailorable magneto-optical materials.
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Affiliation(s)
- Emigdio E Turner
- Department of Chemistry and Chemical Biology, Laboratory for Magneto-Optic Spectroscopy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Trong-Nhan Pham
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19711, United States
| | - Samuel Peter Smith
- Department of Chemistry and Chemical Biology, Laboratory for Magneto-Optic Spectroscopy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Kaytlin N Ward
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19711, United States
| | - Joel Rosenthal
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19711, United States
| | - Jeffrey J Rack
- Department of Chemistry and Chemical Biology, Laboratory for Magneto-Optic Spectroscopy, University of New Mexico, Albuquerque, New Mexico 87131, United States
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Martin MI, Pham TN, Ward KN, Rice AT, Hertler PR, Yap GPA, Gilmartin PH, Rosenthal J. Mapping the influence of ligand electronics on the spectroscopic and 1O 2 sensitization characteristics of Pd(II) biladiene complexes bearing phenyl-alkynyl groups at the 2- and 18-positions. Dalton Trans 2023; 52:7512-7523. [PMID: 37199710 PMCID: PMC10263192 DOI: 10.1039/d3dt00691c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Photodynamic therapy (PDT) is a promising treatment for certain cancers that proceeds via sensitization of ground state 3O2 to generate reactive 1O2. Classic macrocyclic tetrapyrrole ligand scaffolds, such as porphyrins and phthalocyanines, have been studied in detail for their 1O2 photosensitization capabilities. Despite their compelling photophysics, these systems have been limited in PDT applications because of adverse biological side effects. Conversely, the development of non-traditional oligotetrapyrrole ligands metalated with palladium (Pd[DMBil1]) have established new candidates for PDT that display excellent biocompatibility. Herein, the synthesis, electrochemical, and photophysical characterization of a new family of 2,18-bis(phenylalkynyl)-substituted PdII 10,10-dimethyl-5,15-bis(pentafluorophenyl)-biladiene (Pd[DMBil2-R]) complexes is presented. These second generation biladienes feature extended conjugation relative to previously characterized PdII biladiene scaffolds (Pd[DMBil1]). We show that these new derivatives can be prepared in good yield and, that the electronic nature of the phenylalkynyl appendages dramatically influence the PdII biladiene photophysics. Extending the conjugation of the Pd[DMBil1] core through installation of phenylacetylene resulted in a ∼75 nm red-shift of the biladiene absorption spectrum into the phototherapeutic window (600-900 nm), while maintaining the PdII biladiene's steady-state spectroscopic 1O2 sensitization characteristics. Varying the electronics of the phenylalkyne groups via installation of electron donating or withdrawing groups dramatically influences the steady-state spectroscopic and photophysical properties of the resulting Pd[DMBil2-R] family of complexes. The most electron rich variants (Pd[DMBil2-N(CH3)2]) can absorb light as far red as ∼700 nm but suffer from significantly reduced ability to sensitize formation of 1O2. By contrast, Pd[DMBil2-R] derivatives bearing electron withdrawing functionalities (Pd[DMBil2-CN] and Pd[DMBil2-CF3]) display 1O2 quantum yields above 90%. The collection of results we report suggest that excited state charge transfer from more electron-rich phenyl-alkyne appendages to the electron deficient biladiene core circumvents triplet sensitization. The spectral and redox properties, as well as the triplet sensitization efficiency of each Pd[DMBil2-R] derivative is considered in relation to the Hammett value (σp) for each biladiene's R-group. More broadly, the results reported in this study clearly demonstrate that biladiene redox properties, spectral properties, and photophysics can be perturbed greatly by relatively minor alterations to biladiene structure.
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Affiliation(s)
- Maxwell I Martin
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Trong-Nhan Pham
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Kaytlin N Ward
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Anthony T Rice
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Phoebe R Hertler
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Glenn P A Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Philip H Gilmartin
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Joel Rosenthal
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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Larsen S, Adewuyi JA, Ung G, Ghosh A. Transition-Metal Isocorroles as Singlet Oxygen Sensitizers. Inorg Chem 2023; 62:7483-7490. [PMID: 37141580 DOI: 10.1021/acs.inorgchem.3c00782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Building on a highly efficient synthesis of pyrrole-appended isocorroles, we have worked out conditions for manganese, palladium, and platinum insertion into free-base 5/10-(2-pyrrolyl)-5,10,15-tris(4-methylphenyl)isocorrole, H2[5/10-(2-py)TpMePiC]. Platinum insertion proved exceedingly challenging but was finally accomplished with cis-Pt(PhCN)2Cl2. All the complexes proved weakly phosphorescent in the near-infrared under ambient conditions, with a maximum phosphorescence quantum yield of 0.1% observed for Pd[5-(2-py)TpMePiC]. The emission maximum was found to exhibit a strong metal ion dependence for the 5-regioisomeric complexes but not for the 10-regioisomers. Despite the low phosphorescence quantum yields, all the complexes were found to sensitize singlet oxygen formation with moderate to good efficiency, with singlet oxygen quantum yields ranging over 21-52%. With significant absorption in the near-infrared and good singlet oxygen-sensitizing ability, metalloisocorroles deserve examination as photosensitizers in the photodynamic therapy of cancer and other diseases.
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Affiliation(s)
- Simon Larsen
- Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
| | - Joseph A Adewuyi
- Department of Chemistry, University of Connecticut, 55 N. Eagleville Rd, Storrs, Connecticut 06269, United States
| | - Gaël Ung
- Department of Chemistry, University of Connecticut, 55 N. Eagleville Rd, Storrs, Connecticut 06269, United States
| | - Abhik Ghosh
- Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
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