Study on fluorescent switching of naphthopyran with carbazole and pyrene dyad immobilized on SBA-15

A naphthopyran-bridge-carbazole dyad (CzNP), which exhibits both fluorescence and photochromism was synthesized. Then the CzNP was grafted into SBA-15-NH2, with particular focus on how the SBA-15-NH2 affects the photoswitching fluorescence change properties. A double fluorescence photochromic material, which was prepared by reacting 1-Pyrenecardboxaldehyde(PY-CHO):naphthopyran-carbazole(CzNP)=1:1 (molar ratio) with SBA-15-NH2 was also synthesized. Naphthopyran in this two systems displayed excellent photochromic performance. The fluorescent emission was modulated between 'on' and 'off' via the photoisomerization of naphthopyran in high-degree, especially in PY-CzNP-SBA-15-NH2 (>90%) due to the photoinduced energy transfer from pyrene excimers to the opened-form naphthopyran and the photoinduced electron transfer between carbazoles and the opened-form naphthopyran moiety. Both the fluorescence photoswitching CzNP-SBA-15-NH2 and PY-CzNP-SBA-15-NH2 in CH3CN/H2O (v/v, 1:1) solution displayed excellent fatigue resistance. The structural characteristics of CzNP-SBA-15-NH2 and PY-CzNP-SBA-15-NH2 were measured by FTIR spectra, X-ray diffraction (XRD), and Elemental analysis.