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Time- and Concentration-Dependent Reactivity of Cys, Hcy, and GSH on the Diels–Alder-Grafted 1,3,5-Tris Conjugate of Calix[6]arene To Bring Selectivity for Cys: Spectroscopy, Microscopy, and Its Reactivity in Cells

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journal contribution
posted on 07.11.2014, 00:00 by V. V. Sreenivasu Mummidivarapu, Deepthi S. Yarramala, Karuna Kumar Kondaveeti, Chebrolu P. Rao
Herein we report the synthesis and characterization of 7-oxanorbornadiene (OND)-appended 1,3,5-tris conjugate of calix[6]­arene (L2). L2 has been shown to exhibit selective reactivity toward cysteine (Cys) over homocysteine (Hcy) and glutathione (GSH) under stoichiometric conditions. The selectivity of L2 is attributed to the steric crowding of three Diels–Alder centers possessing OND units present on the calix[6]­arene platform, while a control molecular system possessing only one such unit without the calix[6]­arene platform (L1) does not show any selectivity toward Cys. While L2 exhibited spherical particles, its reactivity with Cys resulted in flowerlike morphological features, as revealed by scanning electron microscopy. However, the reaction with GSH did not result in any such morphological features, a result that is in agreement with that observed from fluorescence studies in solution. L2 has been shown to react with Cys present in HeLa and Jurkat E6 cells by fluorescence microscopy.