The spatial effect of near-infrared spectroscopy and its application to the study of supramolecular chemistry.
An unlooked-for experimental observation that in near-infrared spectroscopy (NIR) the absorption peak of the second overtone of aniline adsorbed by 13X molecular sieve nearly disappeared led us investigate a fundamental question: the behavior of NIR when the outside space surrounding a molecule is too small to allow the molecule to vibrate freely. Through NIR of various organic compounds adsorbed by different porous inorganic materials like 13X molecular sieve, silica gel and active aluminium oxide, and NIR of supramolecular cyanuric acid-melamine, we can reasonably confirm a theoretical inference that in the micro-environment above, all intensities of NIR absorbance decrease, and the second overtone decreases more than the first overtone does. Furthermore, one distinct feature of NIR, higher sensitivity to the size of micro-environmental space as compared with mid-infrared (MIR), and its potential application to the study of supramolecular structure are outlined by our experiments.
Cai
Chen-Bo
CB
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
Han
Qing-Juan
QJ
Tang
Li-Juan
LJ
Xu
Lu
L
Wu
Hai-Long
HL
Jiang
Jian-Hui
JH
Yu
Ru-Qin
RQ
D000327:Adsorption; D046911:Macromolecular Substances / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D016062:Porosity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014227:Triazines / Q000737:chemistry
D046911:Macromolecular Substances; D009930:Organic Chemicals; D014227:Triazines; C071913:melamine cyanurate