01854nas a2200157   4500008004100000022001400041245008200055210006900137260007100206300001400277490000600291520125500297100001801552700001801570856010801588       2016                        eng d  a1948-718500aElectrostatic interactions are key to C=O n-pi* shifts: an experimental proof0 aElectrostatic interactions are key to CO npi shifts an experimen  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN  a2270-22750 v73 a<p>Carbonyl n-pi* transitions are known to undergo blue shift in polar and hydrogen-bonding solvents. Using semiempirical expressions, previous studies hypothesized several factors like change in dipole moment and hydrogen-bond strength upon excitation to cause the blue shift. Theoretically, ground-state electrostatics has been predicted to be the key to the observed shifts, however, an experimental proof has been lacking. Our experimental results demonstrate a consistent linear correlation between IR (ground-state phenomenon) and n-pi* frequency shifts (involves both ground and excited electronic-states) of carbonyls in hydrogen-bonded and non-hydrogen-bonded environments. The carbonyl hydrogen-bonding status is experimentally verified from deviation in n-pi*/fluorescence correlation. The IR/n-pi* correlation validates the key role of electrostatic stabilization of the ground state toward n-pi* shifts and demonstrates the electrostatic nature of carbonyl hydrogen bonds. n-pi* shifts show linear sensitivity to calculated electrostatic fields on carbonyls. Our results portray the potential for n-pi* absorption to estimate local polarity in biomolecules and to probe chemical reactions involving carbonyl activation/stabilization.</p>1 aHaldar, Tapas1 aBagchi, Sayan  uhttps://library.ncl.res.in/content/electrostatic-interactions-are-key-co-n-pi-shifts-experimental-proof