NaCl Micro-Crystal as a Molecular Mold for Enhanced Synthesis of Planar Phenazines and Their Applications on Chemosensing and a Full-Color Fluorescent Material

Lei Bian; Jie Ma; Jiebing Ai; Yan Wang; Naiyu Wang; Xiayan Wang; Guangsheng Guo; Qiaosheng Pu

doi:10.1021/acsami.2c03602

NaCl Micro-Crystal as a Molecular Mold for Enhanced Synthesis of Planar Phenazines and Their Applications on Chemosensing and a Full-Color Fluorescent Material

ACS Appl Mater Interfaces. 2022 Aug 31;14(34):39441-39450. doi: 10.1021/acsami.2c03602. Epub 2022 Aug 22.

Authors

Lei Bian¹, Jie Ma^{1

2}, Jiebing Ai¹, Yan Wang¹, Naiyu Wang¹, Xiayan Wang³, Guangsheng Guo³, Qiaosheng Pu¹

Affiliations

¹ State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
² College of Chemical Engineering and Technology, Tianshui Normal University, Tianshui 741001, China.
³ Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China.

PMID: 35993697
DOI: 10.1021/acsami.2c03602

Abstract

NaCl has been successfully used as a template for the synthesis of 2D nanomaterials, but it is seldom used for the construction of flat small organic molecules. Herein, a simple, low-cost, and highly efficient synthesis of phenazines with planar main frames, such as 5-phenyl-5,14-dihydro-5,7,12,14-tetraazapentacene, in the presence of NaCl micro-crystal as a kind of molecular mold is described. The reactants were mixed with NaCl powder and heated to 320 °C for 5 min. Yields >90% were readily achieved after a simple precipitation in water. The effectiveness of NaCl crystal as a mold with HCl was confirmed by comparison with common inorganic salts, SiO₂, and γ-Al₂O₃ with HCl together with combinations including NaNO₃ + HNO₃, Na₂SO₄ + H₂SO₄, NaH₂PO₄ + H₃PO₄, and NaH₂PO₄ + polyphosphoric acid. The mechanism was deduced with the aid of computer simulation, which confirms the stabilization of 5,14-dihydro-5,7,12,14-tetraazapentacene by the NaCl surface. DMSO solution of a product, 1,3-dihydro-imidazo[4,5-b]phenazin-2-one, showed enhanced fluorescence in H₂O, and it was used as a fluorescent probe for pH and Hg²⁺. A full-color material was prepared by mixing precursors of epoxy resin and phenazines, and its fluorescent color could be adjusted by the ratio of phenazines.

Keywords: Hg2+ sensor; NaCl-enhanced synthesis; full-color fluorescence; molecular mold; phenazine.