title: The spatial effect of near-infrared spectroscopy and its application to the study of supramolecular chemistry.
abstract: 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.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Chen-Bo
authors.initials: CB
authors.lastname: Cai
authors.forename: Qing-Juan
authors.initials: QJ
authors.lastname: Han
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Tang
authors.forename: Lu
authors.initials: L
authors.lastname: Xu
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Wu
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Jiang
authors.forename: Ru-Qin
authors.initials: RQ
authors.lastname: Yu
mesh_terms: D000327:Adsorption; D046911:Macromolecular Substances / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D016062:Porosity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014227:Triazines / Q000737:chemistry
chemical_list: D046911:Macromolecular Substances; D009930:Organic Chemicals; D014227:Triazines; C071913:melamine cyanurate