Choi, SY Park, YS Hong, SB Yoon, KB 2024-01-21T19:11:40Z 2024-01-21T19:11:40Z 2022-01-10 1996-10-02 0002-7863 https://pubs.kist.re.kr/handle/201004/144269 The visible absorption band of iodine adsorbed on zeolite blue-shifted with increasing the electropositivity of the countercation and the aluminum content in the framework. This phenomenon was attributed to the increase in the donor strength of the zeolite framework based on the analogous spectral shift of iodine in solution. In support of this, a negative linear correlation was observed between the measured visible bands of iodine adsorbed on various zeolites and their calculated Sanderson's intermediate electronegativities. However, the simultaneous change in the electrostatic field strength within the zeolite pores, as a result of the change in the number and the size of the cation, has to be taken into account in order to interpret the overall spectral shifts more precisely. The iodine band sensitively blue-shifted with decreasing the moisture content in the framework but red-shifted with the loss of NH3 from NH4+-exchanged zeolites. The visible band of iodine also progressively red-shifted with increasing the adsorbed amount, presumably due to the nature of iodine to deplete electron density from the framework. The framework structure also affected the spectral shift of the visible iodine band. The overall results established that iodine can be used as a novel molecular probe for the quantitative evaluation of the zeolite donor strength. English AMER CHEMICAL SOC CATION-EXCHANGED ZEOLITES RAY PHOTOELECTRON-SPECTROSCOPY ALKALI-MODIFIED ZEOLITES NA-Y-ZEOLITE ELECTRIC-FIELD BASIC SITES INFRARED MEASUREMENTS RADICAL CATIONS PHOTOCHEMICAL REACTIVITY CHARGE-DISTRIBUTION Iodine as a visible probe for the evaluation of zeolite donor strength Article 10.1021/ja952112+ 1 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.118, no.39, pp.9377 - 9386 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 118 39 9377 9386 scie scopus A1996VK78000022 2-s2.0-0029855780 Chemistry, Multidisciplinary Chemistry Review CATION-EXCHANGED ZEOLITES RAY PHOTOELECTRON-SPECTROSCOPY ALKALI-MODIFIED ZEOLITES NA-Y-ZEOLITE ELECTRIC-FIELD BASIC SITES INFRARED MEASUREMENTS RADICAL CATIONS PHOTOCHEMICAL REACTIVITY CHARGE-DISTRIBUTION