First example of a molecularly imprinted polymer incorporating a difunctionalized alloxazine flavin isomer

High-quality alloxazine (a flavin isomer) imprinted polymers have been made for the first time. A molecularly imprinted polymer (MIP) for the N1,N3-di-functionalized alloxazine template 2 was made. The MIP prepared for 2 exhibited excellent, highly selective molecular recognition for template 2, as determined by HPLC analysis using columns prepared with the MIP. This has also demonstrated that the core flavin structure can survive the imprinting process.     

Photophysical properties of lumichromes in water

The photophysics of lumichrome, 1-methyllumichrome, and lumiflavin in water solutions have been investigated. Fluorescence lifetimes of 2.7 and 2.2 ns were observed for lumichrome and 1-methyllumichrome, respectively, the corresponding triplet state lifetimes of 17 and 18 μs have been obtained from the transient absorption spectra. Evidence for long lived species with absorption maxima near 450 nm and lifetimes of ca. 400 μs has been found in the transient absorption spectra of both lumichromes. Quantum yields for the sensitised production of singlet oxygen, φ_Δ, are 0.36 and 0.41 for lumichrome and 1-methyllumichrome, respectively, in D₂O.     

Spectroscopy and photophysics of dimethyl-substituted alloxazines

We have calculated the electronic structure and absorption spectra from the ground state and the first triplet excited state for five dimethylalloxazines, using the TD-DFT approach. The results of the calculations were correlated to experimental spectral and photophysical data, including the transient spectra reported here containing triplet–triplet absorption data, using the proximity effect theory to explain the variations of the ISC rates with the substitution pattern and solvent. Additionally, singlet oxygen yields were measured for these compounds, demonstrating their high efficiency as singlet oxygen photosensitizers.     

Synthesis of Flavin–Calix[4]arene Conjugate Derivatives

The synthesis of two new flavin substituted calix[4]arene derivatives, 9 and 10 , is described. The first flavin substituted calix[4]arene derivative 9 was synthesized by the reaction of 3‐methylalloxazine ( 5 ) with 25,27‐bis(3‐bromopropoxy)‐26,28‐dihydroxy‐5,11,17,23‐tetra(tert‐butyl)calix[4]arene ( 4 ) in high yield (92%). The other derivative 10 was prepared from 3‐methylalloxazine‐1‐acetic acid ( 7 ) and 25,27‐bis(3‐cyanopropoxy)calix[4]arene ( 3 ). All new compounds were characterized by a combination of FT‐IR and ¹H‐NMR spectroscopy, and elemental‐analysis techniques.