Porphyrin-anthraquinone dyads: Synthesis, spectroscopy and photochemistry

Kumar, P Prashanth; Premaladha, G; Maiya, Bhaskar G.

doi:10.1007/bf03356116

Cited by 18 publications

(13 citation statements)

References 35 publications

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“…Among the metallated porphyrins, indium complexes exhibited the largest shifts of 8−9 nm, a scenario that has been reported previously [ 42 ]. Similar observations were observed in previous studies [ 41 , 43 , 44 , 45 ]. It is noteworthy that InPP1 and InPP2 were predicted to have the smallest HOMO−LUMO gap values in the geometry optimization calculations ( Figure 3 ), which is consistent with the observed red shifts of the major spectral bands.…”

Section: Resultssupporting

confidence: 93%

Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2: Experimental and Computational Studies

et al. 2021

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The absence of a secure long-term sustainable energy supply is recognized as a major worldwide technological challenge. The generation of H2 through photocatalysis is an environmentally friendly alternative that can help solve the energy problem. Thus, the development of semiconductor materials that can absorb solar light is an attractive approach. TiO2 has a wide bandgap that suffers from no activity in the visible spectrum, limiting its use of solar radiation. In this research, the semiconductor absorption profile was extended into the visible region of the solar spectrum by preparing porphyrin-TiO2 (P-TiO2) composites of meso-tetra(4-bromophenyl)porphyrin (PP1) and meso-tetra(5-bromo-2-thienyl)porphyrin (PP2) and their In(III), Zn(II) and Ga(III) metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed on the porphyrins to gain insight into their electron injection capability. The results demonstrate that P-TiO2 systems merit further in-depth study for applications that require efficient photocatalytic H2 generation.

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Section: Resultssupporting

confidence: 93%

Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2: Experimental and Computational Studies

et al. 2021

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“…From this data, the shorter lifetimes with higher amplitude and longer lifetime components have the same origin as in AQ-(H 2 ) 2 , but the additional shorter lifetime component may be due to the noncovalent interaction of the oxygen lone pair of electrons (anthraquinone) with zinc metal present in other porphyrin of AQ-(Zn) 2 . We believe that this anthraquinone-ligated state is responsible for the additional short-lived component obtained from the TCSPC experiments . In all four investigated solvents, it is observed that the shorter lifetimes of AQ-(H 2 ) 2 have much larger amplitudes relative to the longer lifetime components.…”

Section: Results and Discussionmentioning

confidence: 69%

Bis(porphyrin)–Anthraquinone Triads: Synthesis, Spectroscopy, and Photochemistry

et al. 2013

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Molecular triads based on bis(porphyrin)-anthraquinone having azomethine bridge at the pyrrole-β position have been designed and synthesized. Both free-base AQ-(H2)2 and zinc AQ-(Zn)2 triads are characterized by elemental analysis, MALDI-MS, (1)H NMR, UV-visible, and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical method. The absorption spectra of both Soret and Q-bands of the triads are red-shifted by 12-20 nm with respect to their monomer units. The study supported by theoretical calculations manifests that there exists a negligible electronic communication in the ground state between the donor porphyrin and acceptor anthraquinone of these triads. However, interestingly, both the triads exhibit significant fluorescence emission quenching (51-92%) of the porphyrin emission compared to their monomeric units. The emission quenching is attributed to the excited-state intramolecular photoinduced electron transfer from porphyrins to anthraquinone. The electron-transfer rates (kET) of these triads are found in the range 1.0 × 10(8) to 7.7 × 10(9) s(-1) and are found to be solvent dependent.

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“… a Fluorescence quantum yields (Φ F ) were calculated by the steady-state comparative method using tetraphenylporphyrinatozinc(II) (ZnTPP, Φ F = 0.036 in CH 2 Cl 2 ) as a reference sample. …”

Section: Resultsmentioning

confidence: 99%

Rational Design and Synthesis of OEP and TPP Centered Phosphorus(V) Porphyrin–Naphthalene Conjugates: Triplet Formation via Rapid Charge Recombination

et al. 2021

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Six new "axial-bonding" type "phosphorus(V) porphyrin−naphthalene" conjugates have been prepared consisting of oct a et hyl porp h yrina to pho s pho rus (V ) ( P OEP + )/ tetraphenylporphyrinatophosphorus(V) (PTPP + ) and naphthalene (NP). The distance between the porphyrin and NP was systematically varied using polyether bridges. The unique structural topology of the octaethylporphyrinatophosphorus(V) (POEP + ) and tetraphenylporphyrinatophosphorus(V) (PTPP + ) enabled construction of mono-and disubstituted phosphorus(V) porphyrin−naphthalene conjugates, respectively. The steady-state and transient spectral properties were investigated as a function of redox properties, distance, and molecular topology. Strong electronic interactions between the phosphorus(V) porphyrin and NP in directly bound conjugates were observed. The established energy diagrams predicted reductive electron transfer involving singlet excited phosphorus(V) porphyrin and NP to generate high-energy (∼1.83−2.11 eV) charge-separated states (POEP/ PTPP) • −(NP) •+ . Femtosecond transient absorption spectral studies revealed rapid deactivation of singlet excited phosphorus(V) porphyrin due to charge separation wherein the estimated forward rate constants were in the range of 10 9 −10 10 s −1 and were dependent on the distance between the NP and porphyrins units, as well as the redox potentials of the type of the phosphorus(V) porphyrin. Additionally, due to high exothermicity and low-lying triplet states, the charge recombination process was found to be rapid, leading to populating the triplet states of phosphorus(V) porphyrins.

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Porphyrin-anthraquinone dyads: Synthesis, spectroscopy and photochemistry

Cited by 18 publications

References 35 publications

Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2: Experimental and Computational Studies

Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2: Experimental and Computational Studies

Bis(porphyrin)–Anthraquinone Triads: Synthesis, Spectroscopy, and Photochemistry

Rational Design and Synthesis of OEP and TPP Centered Phosphorus(V) Porphyrin–Naphthalene Conjugates: Triplet Formation via Rapid Charge Recombination

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