Fluorescence properties of riboflavin-functionalized mesoporous silica SBA-15 and riboflavin solutions in presence of different metal and organic cations

Design of Multifunctional Fluorescent Hybrid Materials Based on SiO2 Materials and Core–Shell Fe3O4@SiO2 Nanoparticles for Metal Ion Sensing

“…On another hand, fluorescent chromophore 5‐methoxy‐2‐thiazoles (BTZ‐2) functionalized hybrid sensing probe MSNs‐BTZ‐2 was successfully prepared by Yan and co‐workers, and utilized for the selective detection of proton (H + ) and Cu 2+ in water at pH 7. Fluorescent material MSNs‐BTZ‐2 showed an intense emission band at 400 nm, which was drastically minimized in the presence of Cu 2+ attributed to the formation of a stable MSNs‐BTZ‐2‐Cu 2+ complex and paramagnetic nature of Cu 2+ ion . The calculated detection limit of MSNs‐BTZ‐2 towards Cu 2+ ions was 3.2 × 10 −6 m .…”

“…Fluorescent material MSNs-BTZ-2 showed an intense emission band at 400 nm, which was drastically minimized in the presence of Cu 2+ attributed to the formation of a stable MSNs-BTZ-2-Cu 2+ complex and paramagnetic nature of Cu 2+ ion. [130,131] The calculated detection limit of MSNs-BTZ-2 towards Cu 2+ ions was 3.2 × 10 −6 m. The effective use of this sensor system for multianalyte detection would expressively accelerate general and simple approaches for the identification of various biological and chemical species.…”

Interaction of Alkali Ions with Flavins: Infrared and Optical Spectra of Metal–Riboflavin Complexes

“…Prominent members of the flavin family are lumichrome (LC, R = H at N1 and not at N10), lumiflavin (LF, R = methyl = CH 3 ), riboflavin (RF, R = ribityl = CH 2 (HCOH) 4 H), flavin mononucleotide (FMN, R = ribophosphate), and flavin adenine dinucleotide (FAD, R = ribophosphate + adenine). Flavin-based molecules and complexes are of high biological relevance and can act, for example, as blue-light sensors, light-oxygen-voltage (LOV) receptors, and coenzymes, and participate in the DNA-repair mechanism. − In addition, the interaction of flavins with coordinating metal ions is of special interest. − For example, the photoluminescence of RF strongly depends on the metal···RF interaction. ,, …”

“…To understand the intrinsic properties of flavins and the impact of their interaction with the surrounding environment at the molecular level, spectroscopy of isolated flavins and their complexes is required, in addition to solution experiments. To this end, both experiments − and quantum chemical calculations ,− have been applied extensively to flavins in both condensed and gas phases. However, nearly all spectra have been recorded at room temperature and thus suffer from low spectral resolution arising from inhomogeneous spectral broadening by the solvent or the matrix (in condensed-phase experiments) and/or unresolved vibrational structure, which complicates the assignments of structural isomers (e.g., arising from different (de)­protonation and metalation sites) and the nature of the electronic transitions.…”

“…For instance, the first S 1 ← S 0 (ππ*) absorption band of RF in ethanol recorded at 77 K is observed at 443 nm. However, even cooling the ions down to 77 K does not yield vibrationally resolved spectra (the electronic transition has a width of ∼100 nm), and the effect of solvation remains unclear, with shifts on the order of ∼10 nm of the central band maximum of the S 1 ← S 0 band. , Furthermore, metalated RF complexes have been investigated as well in the condensed phase. ,,− Interestingly, the fluorescence and absorption spectra of RF with various metal salts dissolved in water reveal that the shifts in the electronic transitions can strongly depend on the type of metal ion. For example, while the presence of Na + ions shifts the maximum of the S 1 absorption band by only 1 nm from 446 to 447 nm, Ag + ions cause a much larger red-shift of 24 nm to 470 nm .…”