Intermolecular pyrene excimer formation in zeolites. Decay parameters and ground-state association

Resolution of Ultrafast Pyrene Excimer Emission Rise Times in Zeolites X and Y†

“…Resolution of the monomer emission peaks also increased in the presence of cosolvents (17, 32). These effects of zeolite composition and incorporation of solvents on the relative intensity of monomer and excimer emission are consistent with results in the literature (17, 18, 30, 32), and show that the pyrene/zeolite composites prepared in the present work behave similarly to those prepared in other laboratories.…”

“…This alternative mechanism for pyrene excimer formation is consistent with our time‐resolved data, but it is not compatible with all of the steady‐state fluorescence results obtained by others (8, 17, 18, 30). In particular, excitation spectra obtained with the use of steady‐state fluorescence at high loading levels of pyrene strongly suggest the presence of ground‐state pyrene dimers within zeolite cavities (17, 18).…”

“…The less polar environment within KY also induced a blueshift (31) of the excimer absorption band. In LiY and NaX under steady‐state conditions, the excimer band was weak and difficult to resolve in the steady‐state spectra (18, 30).…”

Molecular Confinement in Nanometer-Size Superlattice Microstructures

“…Pyrene molecules do not preassociate in solution, but this is known to occur inside silica gels 17 and zeolites. 18 We believe that pyrene in our wide pores is forming similar ground-state complexes.…”

Supramolecular photochemistry in zeolites: From catalysts to sunscreens

“…Although the field of zeolite catalysis has been extensively studied over the past four decades, the interest of photochemists in zeolites as host systems for supramolecular photochemistry is relatively recent [1,[3][4][5][6][7]. It was not until the mid-1980s that researchers began to explore the use of zeolite materials as a constrained media for the control of photochemical and photophysical processes [8][9][10]. The acknowledgment that zeolites are convenient and versatile solid hosts for a huge estimated to be 370 Å 3 , corresponding to a free diameter of about 8.9 Å [26].…”