Xiao-Fei Gu,Yue Zhao,Kan Li,Meng-Xiang Su,Fang Yan,Bo Li,Ying-Xiang Du,Bin Di
Structure elucidation of volatile aromatic isomers at trace level has long been considered as an elusive task, due to their structural similarities and similar polarities, even with the aid of many spectroscopic techniques such as mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Single-crystal X-ray diffraction (SCD) is recognized as one of the most powerful structural elucidation techniques. The recently developed crystalline sponge method overcomes the intrinsic limitation of SCD that the target molecules must be single crystals, being able to analyze non-crystalline and trace-amount compounds without any special treatment. In order to investigate whether the crystalline sponge method could be used for the structure elucidation of closely related isomers or other volatile and even oily compounds in complex mixtures at trace level, we combined HPLC separation with the crystalline sponge method for X-ray crystallographic analysis. In this paper, two pairs of volatile aromatic isomers including cis / trans isomers of asarone and positional isomers of carvacrol and thymol, as well as the main volatile component in essential oil extracted from Acorus Tatarinowii , were first isolated by HPLC and encapsulated into the crystalline sponge then elucidated by X-ray crystallographic analysis. Direct observation of these volatile compounds by X-ray crystallography was achieved using only microgram quantities without crystallization or derivatization. Unambiguous identification of these compounds was realized without reference standards. This strategy offers a promising platform capable of providing high-confidence detailed structural information of closely related isomers as well as other volatile and even oily compounds in complex mixtures in microgram quantities.
Anti-counterfeiting technologies are crucial for securing the authenticity and proof of commodities, in which the optical information encryption/decryption has attracted extensive attention for its overriding advantages of visibility and convenience. Inspired by the unique transparency transformation phenomenon of Diphylleia grayi petals, a controllable hydrophilic/superhydrophobic patterned coating with water-triggered opaque to translucent transition is proposed through the construction of a superhydrophobic coating, subsequent air plasma etching under a mask, and final hydrophilic modification to introduce stable invisible patterns. The superhydrophobic region exhibits great water repellency with a water contact angle (WCA) at 157°, while the hydrophilic region quickly absorbs water with a WCA at 61°. The patterned coating presents an opaque state for the serious light scattering induced by the rough microstructure and large refractive index difference between the coating and air, while the hydrophilic patterns on the coating transform to translucent after water infiltration for the reduced roughness and close refractive indexes of the coating and water. The information revealing is rapid and reversible, and demonstrates heat and long-term stability and great reusability. The findings conceivably stand out as a new methodology to fabricate controllable superwettable coatings with optical information encryption/decryption capability for application in anti-counterfeiting.
危险品化学品经营许可证（带存储）