Novel Riboflavin-Inspired Conjugated Bio-Organic Semiconductors

Abstract

Flavins are known to be extremely versatile, thus enabling routes to innumerable modifications in order to obtain desired properties. Thus, in the present paper, the group of bio-inspired conjugated materials based on the alloxazine core is synthetized using two efficient novel synthetic approaches providing relatively high reaction yields. The comprehensive characterization of the materials, in order to evaluate the properties and application potential, has shown that the modification of the initial alloxazine core with aromatic substituents allows fine tuning of the optical bandgap, position of electronic orbitals, absorption and emission properties. Interestingly, the compounds possess multichromophoric behavior, which is assumed to be the results of an intramolecular proton transfer.

Tunable Properties of Nature-Inspired N,N′-Alkylated Riboflavin Semiconductors

“…A similar trend was also observed for progressively expanded N10-butyl substituted flavins [43]. Moreover, the studied materials provided high thermal stability reaching up to 443 • C [42]. The synthesized flavins were proposed as possible promising materials for biomimetic energy storage or photocatalytic oxygen evolution due to their tunable optical and electronic properties.…”

“…A strong dependence of the frontier molecular orbitals (FMO) energies determined by cyclic voltammetry on the size of the fused π-conjugated system was observed. The LUMO energies increased with enlarging of the π-system, while they remained virtually invariable for the non-fused flavin derivatives with alloxazine π-conjugated core [42]. It was shown that expansion of the π-conjugated system provided tunable light absorption reaching up to 700 nm.…”

“…On the contrary, the effect of the expanding of the π-conjugated system on the optical and electronic properties of flavins is less explored, although changes in electrochemical properties and bathochromic shifts of the absorption maxima are anticipated [41]. A study investigating a series of flavins with progressively expanded fused π-systems and a series of non-fused derivatives was reported [42]. A strong dependence of the frontier molecular orbitals (FMO) energies determined by cyclic voltammetry on the size of the fused π-conjugated system was observed.…”

“…The synthesized flavins were proposed as possible promising materials for biomimetic energy storage or photocatalytic oxygen evolution due to their tunable optical and electronic properties. On the other hand, the NH-unsubstituted flavin derivatives suffer from poor solubility in common organic solvents due to strong intermolecular hydrogen-bonding which limits their technological processability [42,44].…”

Potential photoacid generators based on oxime sulfonates

“…There are a number of erroneous literature reports claiming that the bis-oxime of benzil can be formed under these conditions. [17][18][19] Both syn and anti isomers of benzil derivative 10 have been claimed as they can be separated and the anti isomers form metal-ion complexes. 16 We found that compounds 9 and 10 were both sulfonated with either 4-methylbenzenesulfonyl chloride or propylsulfonyl chloride to give compounds 11-14 which are potential photoacid generators ( Figure 6).…”