Vibrational spectroscopy of the cryogenically cooled O- and N-protomers of 4-aminobenzoic acid: Tag effects, isotopic labels, and identification of the E,Z isomer of the O-protomer

Collision-assisted stripping for determination of microsolvation-dependent protonation sites in hydrated clusters by cryogenic ion trap infrared spectroscopy: the case of benzocaineH+(H2O)n

“…3,4 In general, the protonation site of an organic molecule highly depends on the surrounding solvent. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] This solvent-dependent behavior is particularly prominent for molecules with multiple basic sites. For example, benzocaine (BC), which has both carbonyl and amino groups, is most stable in its NH 2 -protonated form (N-protomer, H + BC(N)) in polar solvents, whereas the CO-protonated form (O-protomer, H + BC(O)) is most stable in the gas phase (Fig.…”

“…14,15 This solvent-dependent protonation-site switching is not only found in BC but prevails in other (bio-)organic molecules. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Much effort has been devoted to microsolvated clusters, in which an ion is solvated by a few to several hundreds of molecules, 14,[34][35][36] because the degree of solvation can be tuned by controlling the type and numbers of solvent molecules.…”

Measurement of the Population of Electrosprayed Deprotomers of Coumaric Acids Using UV–Vis Laser Photodissociation Spectroscopy

“…Toward this end, recent studies have investigated the possibility of applying in situ spectroscopy to identify correctly electrosprayed protomers or deprotomers. 2 , 4 , 6 − 8 , 11 …”

Application of continuous wave quantum cascade laser in combination with CIVP spectroscopy for investigation of large organic and organometallic ions

“…72 Mark Johnson's lab reported that 4-aminobenzoic acid (4ABA) could also reside in Oor N-protomeric states. 73 As in the previous case, the O-protomer of 4ABA is about 10 kcal/mol more stable than the N-protomer. However, depending on the hydroxyl groups' mutual positions in protonated carboxyl moiety, the difference could be reduced to about 5 kcal/mol.…”