Studies on the riboflavin-resorcinol interaction in an aqueous medium and its pH dependence.
The equilibrium constants, K', for the formation of the molecular association complex between riboflavin and resorcinol in the pH range 6-8 were found to be in the range 5-25 mol(-1)dm(3) by difference absorption spectroscopy. The equilibrium constants from emission spectroscopy were estimated to be in the range 38-55 mol(-1)dm(3) over the same pH range. Both sets of K' show a remarkable dependence on pH. The equilibrium constants K(A) and K(B) describing the interaction of riboflavin with neutral and ionic forms of resorcinol, respectively, obtained by resolving K', shows that K(B) is much greater than K(A). Molecular modeling studies suggest a stacked conformation of the two components in the complexed form. The interaction energies obtained from modeling studies also suggest a stronger interaction between the ionic form of resorcinol and riboflavin.
Datta
Silpi
S
Department of Chemistry, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, India.
Mukhopadhyay
Chaitali
C
Bhattacharya
Subirnath
S
Bose
Swapan Kumar
SK
D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009566:Nitrates; D017680:Potassium Compounds; D012118:Resorcinols / Q000737:chemistry*; D012256:Riboflavin / Q000737:chemistry*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014867:Water
D007202:Indicators and Reagents; D009566:Nitrates; D017680:Potassium Compounds; D012118:Resorcinols; D012996:Solutions; D014867:Water; C023844:potassium nitrate; D012256:Riboflavin; C031389:resorcinol