![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
A cyclohexane-trans-1,2-diimine capped conjugate of 1,3-calix[4]arene (L) has been synthesized and characterized using different analytical and spectral techniques. L has been shown to be sensitive toward Al3+ by exhibiting ~45-fold enhancement in its emission intensity at 445 nm upon complexation. All the other 15 metal ions showed almost no or minimal change in the fluorescence intensity of the L supporting that none of those 15 ions is sensed by L. The complexation between L and Al3+ has been further confirmed by absorption spectroscopy, isothermal titration calorimetry and ESI MS. The isotopic peak pattern of the ESI MS peak clearly confirmed the presence of aluminum in the 1:1 complex formed. The need for the flexible cap moiety for bringing selectivity to Al3+ was proven by comparing the titration studies with the corresponding control molecules. The sensing of Al3+ by L in the solid powder was demonstrated by fluorescence microscopy. The supramolecular behavior of L changes from simple spherical type morphology in L to an aggregated micro pots and fibers upon Al3+ binding. The DFT computational study yielded a distorted tetrahedral complex of the dianionic receptor resulting in AlN2O2 core.
Acknowledgments
CPR acknowledges financial support from the DST/SERB, J. C. Bose National Fellowship and IIT Bombay for Institute Chair Professorship. AN & DSY acknowledge UGC for their SRF fellowship. BS gratefully acknowledges the financial support of the Natural Science Foundation of China (Grant No. 21650110464). We thank the FEGSEM central facility of IIT Bombay for providing the service. We thank Dr. Ravinder Kandi for providing the service on fluorescence microscopy for powders.