Photoinduced electron transfer from chlorin p6 to methyl viologen in aqueous micelles

Mukherjee, Tushar Kanti; Mishra, Padmaja P.; Datta, Anindya

doi:10.1016/j.cplett.2005.03.055

Cited by 33 publications

(52 citation statements)

References 28 publications

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“…A representative selection is shown in Scheme 87. The amphiphilic chlorins that lack gemdimethyl groups include the following: (1) derivatives of chlorophylls such as pheophorbide a (obtained upon acidic demagnesiation and hydrolysis of the phytyl ester), 65 chlorin e 6 423 and p 6 424 (derived by saponification, opening of the isocyclic ring, and oxidation), a chlorin-imide ( 198 ) derived from chlorophyll a , 425 and the semicarbazone of chlorophyll b and Girard’s T reagent ( 199 ); 426 (2) a tetraarylchlorin prepared by hydrogenation of the corresponding porphyrin ( 200 ); 427 and (3) a chlorin derived by semisynthesis from the porphyrin heme ( 201 ). 428 …”

Section: Smorgasbord Of Chlorinsmentioning

confidence: 99%

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

2015

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Woodward reported his infamous synthesis of chlorin e 6 trimethyl ester, a known synthetic precursor to chlorophyll a. [59][60][61][62][63][64]124 The work was posited on a half-century of intensive studies by many investigators in tetrapyrrole chemistry and began a decade after the close of Fischer's lifetime of research 125−128 (which included an uncompleted synthetic program directed toward chlorophylls 15 ). Indeed, "he read all the umpteen papers on the chlorophylls written by Willstaẗter and Fischer, including the experimental parts." 129 The Woodward synthesis of chlorin e 6 trimethyl ester required 46 steps, of which 24 were spent on converting the sole precursor, Knorr's pyrrole, to the four pyrroles destined to form rings A−D; 7 additional steps accrued to obtain the dipyrromethanes that constitute the Eastern and Western halves (Scheme 13, the step numbers are identical to those shown in ref 64.). The first step formed the Knorr pyrrole (in several kg quantities), the next 24 steps were divided into four parallel paths, whereas the remaining 21 steps proceeded in linear fashion. Remarkable features of the synthesis include the directed intramolecular joining (via an imine) of the Eastern and Western halves (step 33), construction of the acrylate Scheme 10. Hydrogenation of a Porphyrin to Form a Chlorin Scheme 11. Representative meso-Tetraarylchlorins Scheme 12. Methyl Pyropheophorbide a

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Section: Smorgasbord Of Chlorinsmentioning

confidence: 99%

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

2015

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“…[1][2][3][4][5][6][7] Due to such importance, ET reactions in various microheterogeneous assemblies have been investigated very extensively with the ultimate aim of achieving control over the dynamics, energetics and mechanism of the ET processes. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] In microheterogeneous media, the degree of hydration (i.e. micropolarity) not only determines the rate of the solvent relaxation process but also plays an important role in determining the microviscosity for the reaction environment.…”

Section: Introductionmentioning

confidence: 99%

Tuning of electron transfer reactions in pluronic–surfactant supramolecular assemblies

Verma

Pal

2015

Phys. Chem. Chem. Phys.

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Photoinduced electron transfer (ET) reaction between an anionic acceptor, coumarin-343 (C343), and a neutral donor, N,N-dimethylaniline (DMAN), has been investigated in composite supramolecular assemblies (mixed micelles) comprised of a pluronic copolymer (P123: EO20-PO70-EO20 or F88: EO103-PO39-EO103 where EO: ethylene oxide and PO: propylene oxide) and a cationic surfactant (CTAC: cetyltrimethylammonium chloride), following fluorescence quenching studies. Systematic increase in the quenching rates for the studied donor-acceptor system with the increasing CTAC to pluronic molar ratio in the mixed micelles demonstrates a large modulation in the ET rates. The mixed micellar systems in the present cases are formed through the incorporation of the hydrocarbon chains of CTAC into the poly-PO core of the pluronic micelles whereby the cationic head groups of CTAC are placed at the periphery of the micellar core, protruded into the hydrated poly-EO corona region, leading to the formation of a positively charged layer deep inside these mixed micelles. Thus, the anionic C343 dye, initially dissolved at the micelle-water interface, experiences a gradually increasing electrostatic attraction and is therefore systematically dragged deeper inside the micellar corona, as the CTAC composition is increased in the mixed micellar systems. Consequently, the ET rate of the C343-DMAN pair undergoes a large enhancement in the studied mixed micellar systems with the increasing CTAC to pluronic molar ratio. The present strategy of modulating ET reactions using such composite supramolecular assemblies can find applications in areas where bimolecular ET is an integral reaction step.

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“…Time‐resolved fluorescence measurements were performed at a magic angle using a picosecond pulsed diode laser based TCSPC fluorescence spectrophotometer from IBH, UK. The fluorescence decays were fitted to biexponential functions by iterative reconvolution using the IBH DAS 6.0 software 44…”

Section: Methodsmentioning

confidence: 99%

Acid‐induced loss of functional properties of bacterial cell division protein FtsZ: Evidence for an alternative conformation at acidic pH

Santra¹,

Panda²

2007

Proteins

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Several types of bacteria live in highly acidic environments. Since the assembly of FtsZ is important for bacterial cytokinesis, the effects of pH on the assembly and structural properties of FtsZ were examined. FtsZ retained GTP binding ability but lost GTPase activity at pH 2.5. In the presence of GTP, FtsZ formed protofilaments at pH 7 while it formed aggregates instead of protofilaments at pH 2.5, indicating that GTP hydrolysis is important for the assembly of FtsZ into protofilaments. Further, the acid-inactivated state of FtsZ recovered its structural and functional properties upon refolding at pH 7, indicating that the cellular functions of FtsZ may be restored after removal of the external stress. In addition, the affinity of 1-anilinonaphthalene-8-sulfonic acid (ANS) binding to FtsZ was found to be higher at pH 2.5 than at pH 7. FtsZ-ANS complex had a higher quantum yield and lifetime at pH 2.5 than at pH 7. However, the secondary structures of FtsZ were similar at pH 7 and 2.5, indicating that FtsZ attained an alternatively folded state (A) at pH 2.5, which has some characteristics of a molten-globule-like state. The A state was more stable than the native state (N) against urea-induced unfolding. The transition from N to A state involves the formation of aggregates of FtsZ (I). The association of FtsZ monomers occurred in the narrow pH range (3.2-2.8) and it was found to be a fully reversible process. The results suggest that a productive intermediate (I) forms in the acid-induced unfolding pathway of FtsZ and that the unfolding pathway may be minimally described as N <==> I <==> A.

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Photoinduced electron transfer from chlorin p6 to methyl viologen in aqueous micelles

Cited by 33 publications

References 28 publications

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

Tuning of electron transfer reactions in pluronic–surfactant supramolecular assemblies

Acid‐induced loss of functional properties of bacterial cell division protein FtsZ: Evidence for an alternative conformation at acidic pH

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