Construction And Bidirectional Energy Transfer Properties Based On The Quadruple Hydrogen-Bonded Supramolecular Assemblies

Hydrogen-bonding interactions play an important role in natural biological system.The quadruple hydrogen-bonds(2-ureido-4(1H)-pyrimidone, UPy) have been widely employed to construct supramolecular self-assembly systems due to their high directivity, selectivity and association constants. It is significant to study the energy transfer process based on quadruple hydrogen-bonded supramolecular system for understanding the photosynthesis in nature, designing molecular photovoltaic device and artificial solar energy conversion process.Boron dipyrrolemethene, BODIPY, is a highly fluorescent dye with excellent photophysical properties, which have drawn much attentions in recent years. The BODIPY dyes have been applied in various fields such as fluorescent probes, biological imaging and photodynamic therapy. In this thesis, we have designed and synthesized two quadruple hydrogen-bonding substituted BODIPY dyes(Bodipy-UPy and I-Bodipy-UPy), and studied their photophysical properties, as well as the energy transfer processes of the supramolecular assemblies. The results are as followings:(1) Both of the Bodipy-UPy and I-Bodipy-UPy have excellent photophysical properties. Molar extinction coefficient of the Bodipy-UPy is 6.89×104 mol·L-1·cm-1 and the I-BodipyUPy is 7.41×104 mol·L-1·cm-1. The fluorescence quantum yield of the Bodipy-UPy is 0.56. It is observed that there is a near infrared phosphorescence peak at 747 nm for I-Bodipy-UPy at 77 K, which indicate the presence of iodine atom can effectively promote the spin-orbit coupling and improve intersystem crossing possibility of the singlet excited state to the triplet excited state.(2) supramolecular assemblies that formed by the molar ratio of 1:1 between Bodipy-UPy and I-Bodipy-UPy can have an efficient bidirectional energy transfer process. The singlet energy transfer efficiency is 54.5%. The so-called “Ping-Pong bidirectional energy transfer processes” can be proved by steady state UV-vis absorption spectra, fluorescence emission spectra and nanosecond time-resolved transient difference absorption spectra.