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Spectroscopic study of porphyrin self‐assembly: Role of pH, time, and chiral template
Author(s) -
Thorpe Stephanie L.,
Snyder Gabrielle N.,
Mammana Angela
Publication year - 2020
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.23140
Subject(s) - chemistry , circular dichroism , porphyrin , supramolecular chemistry , chirality (physics) , enantiomer , supramolecular chirality , ternary operation , self assembly , cotton effect , optical rotation , polyglutamic acid , stereochemistry , atropisomer , crystallography , ternary complex , photochemistry , organic chemistry , crystal structure , biochemistry , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , enzyme , computer science , programming language , quark
Abstract In this study, we performed an ultraviolet‐visible (UV‐Vis) and circular dichroism (CD) spectroscopic analysis of the binary and ternary supramolecular structures formed by self‐assembling the following three water‐soluble porphyrins with and without a chiral template: the negatively charged, meso ‐Tetra(4‐sulfonatophenyl) porphine (H 2 TPPS 4− ); the positively charged meso ‐ trans ‐(di( N ‐methyl‐4‐pyridyl)diphenyl) porphine ( trans ‐DmPyDPP) and meso ‐ cis ‐(di( N ‐methyl‐4‐pyridyl)diphenyl) porphine ( cis ‐DmPyDPP). Polyglutamic acid (both L and D enantiomers) was selected as the chiral template due to its ability to change secondary structure with pH. The propensity for the porphyrins to show an induced CD in the presence of polyglutamic acid is demonstrated. The induced chirality of all supramolecular structures was found to depend on the pH of the solution, the chirality of the polymer, and the order of addition of the positively and negatively charged porphyrins (for ternary complexes). Of particular interest is that the interaction of H 2 TPPS 4− with the chiral scaffold seems to undergo a dynamic rearrangement of the supramolecular structure as evident from the change in the CD spectrum over time. Moreover, experiments with ternary complexes suggest that the preferential interaction of trans ‐DmPyDPP with the random coil of the polymer shows promise as a sensor of protein secondary structure.