Synthesis and characterization of thiacalix[3]triazine and 1,3,5-tris(4- bromophenyl)benzene for chemsensor application

Trang 163 Synthesis and characterization of thiacalix[3]triazine and 1,3,5-tris(4bromophenyl)benzene for chemsensor application  Ha Tran Nguyen  Anh Tuan Luu University of Technology, VNU-HCM Email: nguyentranha@hcmut.edu.vn (Received on 15June 2017, accepted on 26June 2017) ABSTRACT The synthesis of thiacalix[3]triazines and 1,3,5tris(4-bromophenyl)benzene have been synthesized via simple steps and was characterized to determine the chemical structure. The structure of Thiacalix[3]triazines was characterized via H NMR and C NMR that conformed the expected structure of compound. In addition, the thiacalix[3]triazines exhibited the λmax at 560 nm and λonset at 720 nm which corresponding to the bandgap of 1.7 ev. Thiacalix[3]triazines, cyclotrimeric metacyclophanes with direct S linkages between the heteroaryl constituents, were shown to associate with anion that could be useful for chemsensor application.


INTRODUCTION
Heteracalixarenes have gained considerable attention in recent years due to their potential value in supramolecular chemistry. In particular, thiacalix[3]triazine is a kind of class of calixarenes which have been proven to be suitable macrocyclic scaffolds depend on anion binding moieties [1]. The heteroatom bridges allow tuning of the macrocycle size, the electron density on the arene building blocks and the preferred conformation provide additional binding sites towards a perfect (induced) fit of a desirable guest molecule. Among these heterametacyclophanes, the thia analogues or thiacalixarenes have been studied most intensively and they are widely recognized as effective receptors for small organic compounds and heavy/transition metals [1-3]. The fields of oxaand azacalixarenes have also steadily grown [4][5][6][7][8][9][10], both in synthetic scope and supramolecular applications.
However, extension of heteracalixarene chemistry to the larger group through chalcogen elements was noticeably absent in the literature until a very recent communication on.
Thiacalix[3]triazine is constructed from 1,3,5triazines, enforced as electron-deficient host for halide ion binding through anion-π interactions [10]. Thiacalix[3]triazine can be prepared by condensation of a dichloro-1,3,5-triazine with sulfide ion. The synthesis of thiacalix[3]triazines with peripheral phenol or tert-butyl substituents from the reaction of corresponding 2,4-dichloro-1,3,5-triazine with NaSH or alternatively Na2S has been reported. Thiacalix[3]triazine has been shown to interact with non-protic and less-acidic protic anions via the anion association mechanism, and with more-acidic protic anions following the protonation mechanism In this contribution, here we report the synthesis and characterization of thiacalix[3]triazine and its potential application as chemsensor for detecting of anion in the environment. were purchased from Fisher/Acros (Bridgewater, NJ, USA) and used as received.

Characterization
1 H NMR and 13 C NMR spectra were recorded in deuterated chloroform (CDCl3) with tetramethylsilane as an internal reference, on a Bruker Avance 300MHz. Fourier Transform Infrared (FTIR) spectra, collected as the average of 64 scans with a resolution of 4 cm -1 , were recorded from a KBr disk on the FTIR Bruker Tensor 27. UV-visible absorption spectra of polymers in solution and polymer thin films were recorded on a Shimadzu UV-2450 spectrometer over the wavelength range 300-700 nm. Fluorescence spectra were measured on a Horiba IHR 325 spectrometer.

Synthesis of 2,4-dichloro-6-phenoxy-1,3,5triazine
Cyanuric chloride (7) (1.840 g, 10 mmol) was dissolved in acetone (100 mL) and cooled to 0 C. In a separate flask, phenol (0.94 g, 10 mmol) was reacted with NaOH (0.400 g, 10 mmol) in water (100 mL) to form a clear aqueous solution. Then the aqueous solution was added dropwise to the cyanuric chloride solution. After stirring at 0 C for 8 h, the mixture was poured into water (100 mL) to form a white precipitate. The white precipitate was filtered and washed with water and ethanol. The product was purified by recrystallization with hexane to give a white solid. Yield: 80 %.

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The chemical structure of 1,3,5-tris(4bromophenyl)benzene compound monomer was also elucidated by 1 H NMR (Figure 2). 1 H NMR spectrum of 1,3,5-tris(4-bromophenyl)benzene showed the signals attributed to the phenyl protons in range of 7.5 to 7.8 ppm with those corresponding all protons of phenyl rings. The integration of proton signal was also reasonable with structure of 1,3,5-tris(4bromophenyl)benzene.