Revisiting noncovalent So2- amine chemistry: an indicator-displacement assay for colorimetric detection of So2.
A supramolecular approach for potential detection of SO2 is presented, which is based on the "old" donor-acceptor chemistry between SO2 and amines and includes an indicator-displacement assay. When amines were added to Zn-tetraphenylporphyrin 1 in CHCl3, the solution changed from red to dark green. A bathochromic shift of Deltalambda approximately 10 nm was observed for the Soret band, indicating the formation of 1*amine complexes. After this, SO2 gas was introduced, and the original red color of the solution was restored. The Soret band returned to its position for free porphyrin 1. The 1*amine complexes dissociated, and new SO2*amine adducts formed. Porphyrin 1 thus served as an indirect colorimetric indicator for SO2. The system discriminates between SO2 and such typical exhaust gases as COX, NOX, and H2O. From the indicator-displacement assay, the Kassoc values between 1000 and 30 000 M-1 for SO2*amine complexes were determined, which are comparable to those obtained by direct titration experiments between SO2 and the amines. Spectroscopic features of SO2*amine complexes are also presented.
Leontiev
Alexander V
AV
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019-0065, USA.
Rudkevich
Dmitry M
DM
D000588:Amines / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods; D007202:Indicators and Reagents; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D012680:Sensitivity and Specificity; D013458:Sulfur Dioxide / Q000032:analysis / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D000588:Amines; D007202:Indicators and Reagents; D009942:Organometallic Compounds; D013458:Sulfur Dioxide; D015032:Zinc