1502-47-2Relevant articles and documents
Use of melem as a nucleophilic reagent to form the triphthalimide C 6N7(phthal)3-New targets and prospects
Schwarzer, Anke,Boehme, Uwe,Kroke, Edwin
, p. 12052 - 12058,7 (2012)
Melem (1), as one of the most important representatives of the tri-s-triazine compounds, can be used as a nucleophilic reagent in reactions with phthalic acid derivatives. The synthesis of 2,5,8-triphthalimido-tri-s- triazine (C6N7(phthal)3, 2) was investigated starting from phthalic anhydride or phthalic dichloride in various solvents, at different temperatures as well as in the solid state. NMR measurements (solution and solid state), IR spectroscopy and elemental analysis indicated the formation of a cyclic imide. Single-crystal structure analysis of a 1:1 adduct of 2 with nitromethane proved the molecular structure expected for a phthalimido-s-heptazine. DFT calculations were performed to obtain a better insight into the structural features of compound 2, especially the interaction of the carbonyl groups with the tri-s-triazine nitrogen atoms. The title compound 2 shows promising properties: it is thermally stable up to 500 °C in air and shows strong photoluminescence with a maximum emission at around 500a nm. The potential of the nucleophilic reaction of melem with other strong electrophiles provides new targets and prospects. Copyright
Functionalizing carbon nitride with heavy atom-free spin converters for enhanced 1O2 generation
Wu, Wenting,Han, Congcong,Zhang, Qinhua,Zhang, Qinggang,Li, Zhongtao,Gosztola, David J.,Wiederrecht, Gary P.,Wu, Mingbo
, p. 222 - 229 (2018)
Carbon nitride as a metal-free conjugated polymer exhibits an intriguing prospect for the design of advanced photosensitizers for singlet oxygen (1O2) generation. However, the intersystem crossing (ISC) process is quite insufficient in carbon nitride, limiting the 1O2 generation. Here, we report a facile and general strategy to confined benzophenone as a heavy atom-free spin converter dopant in carbon nitride via the facile copolymerization. With proper energy level matching between the heavy atom-free spin converter and various ligands based on carbon nitride precursors, the proper combination can decrease the singlet-triplet energy gap (ΔEST) and hence generate 1O2 effectively. Due to its significant and selectivity for 1O2 generation, the as-prepared carbon nitride-based photosensitizer shows a high selective photooxidation activity for 1,5-dihydroxy-naphthalene (1,5-DHN). The product yield reached 71.8% after irradiation for 60 min, which was higher than that of cyclometalated PtII complexes (53.6%) in homogeneous photooxidation. This study can broaden the application of carbon nitride in the field of selective heterogeneous photooxidation due to simple operation, low cost, and high efficiency, making it a strong candidate for future industrialization.
Photophysics and Photocatalysis of Melem: A Spectroscopic Reinvestigation
Wen, Jing,Li, Ruiyu,Lu, Rong,Yu, Anchi
, p. 1060 - 1066 (2018)
Graphitic carbon nitride (g-CN) is one potential metal-free photocatalyst. The photocatalytic mechanism of g-CN is related to the heptazine ring building unit. Melem is the simplest heptazine-based compound and g-CN is its polymeric product. Thus, studies on the photophysical properties of melem will help to understand the photocatalytic mechanism of heptazine-based materials. Herein, the spectroscopic features of melem were systematically explored through measuring its absorption spectrum, fluorescence spectrum, and fluorescence decay. Both fluorescence spectroscopy and fluorescence decay measurements show that the condensation of melamine to melem causes stronger photoluminescence, whereas the condensation of melem to g-CN causes weaker photoluminescence. In addition, all observations reveal that a mixture of monomer melem and its higher condensates is more easily obtained during the preparation of melem, and that the higher condensates of melem affect the photophysical properties of melem dominantly. The photocatalytic hydrogen evolution of melem has also been measured and the monomer melem has negligible photoinduced water-splitting activity.
Single-crystalline melem (C6N10H6) nanorods: A novel stable molecular crystal photocatalyst with modulated charge potentials and dynamics
Lei, Renbo,Du, Bingsheng,Lai, Xiaofang,Wu, Jing,Zhang, Zhihua,Liu, Shengwei,Wu, Rong,Li, Xin,Song, Bo,Jian, Jikang
, p. 13234 - 13241 (2019)
It is still challenging to control the crystallization and morphologies of molecular crystal nanostructures with excellent photocatalytic activities. In this study, single-crystalline melem (C6N10H6) nanorods (MNRs) were prepared by a facile thermal polymerization route under a flowing argon atmosphere. Compared with the bulk melem counterpart and g-C3N4, the MNRs exhibited substantially improved efficiency and stability towards the photodegradation of diverse organic pollutants including methyl orange, rhodamine B, and methylene blue. Moreover, the average photocatalytic hydrogen evolution rate of MNRs was about 2.6 folds higher than that of bulk melem under the same conditions. The enhanced photocatalytic redox performance of MNRs arises from the single-crystal nature and novel one-dimensional (1D) nanorod morphology, contributing to elevated conduction band potentials and promoting charge transport dynamics. This study not only reports single-crystalline melem 1D nanostructures as novel highly efficient and stable molecular-crystal photocatalysts, but also reveals the important roles of synergetic tuning of charge potentials and dynamics in enhancing the photocatalytic activity of molecular-crystal photocatalysts.
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Framework for Photocatalytic, Photovoltaic and Adsorbent Applications
Kumar, Pawan,Vahidzadeh, Ehsan,Thakur, Ujwal K.,Kar, Piyush,Alam, Kazi M.,Goswami, Ankur,Mahdi, Najia,Cui, Kai,Bernard, Guy M.,Michaelis, Vladimir K.,Shankar, Karthik
, p. 5415 - 5436 (2019)
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction down to 1.76 eV. XRD, He-ion imaging, HR-TEM, EELS, PL, fluorescence lifetime imaging, Raman, FTIR, TGA, KPFM, XPS, NMR and EPR clearly show that the properties of C3N5 are distinct from pristine carbon nitride (g-C3N4). When used as an electron transport layer (ETL) in MAPbBr3 based halide perovskite solar cells, C3N5 outperformed g-C3N4, in particular generating an open circuit photovoltage as high as 1.3 V, while C3N5 blended with MAxFA1-xPb(I0.85Br0.15)3 perovskite active layer achieved a photoconversion efficiency (PCE) up to 16.7%. C3N5 was also shown to be an effective visible light sensitizer for TiO2 photoanodes in photoelectrochemical water splitting. Because of its electron-rich character, the C3N5 material displayed instantaneous adsorption of methylene blue from aqueous solution reaching complete equilibrium within 10 min, which is significantly faster than pristine g-C3N4 and other carbon based materials. C3N5 coupled with plasmonic silver nanocubes promotes plasmon-exciton coinduced surface catalytic reactions reaching completion at much low laser intensity (1.0 mW) than g-C3N4, which showed sluggish performance even at high laser power (10.0 mW). The relatively narrow bandgap and 2D structure of C3N5 make it an interesting air-stable and temperature-resistant semiconductor for optoelectronic applications while its electron-rich character and intrasheet cavity make it an attractive supramolecular adsorbent for environmental applications.
From Heptazines to Triazines – On the Formation of Poly(triazine imide)
Kessler, Fabian K.,Schnick, Wolfgang
, p. 857 - 862 (2019)
Poly(triazine imide), a 2D extended carbon nitride network compound that is obtained from ionothermal synthesis in LiCl/KCl or LiBr/KBr salt melt has been known for over a decade. We now have investigated the formation process of this material starting from various triazine- and heptazine-based precursors as well as the differences between ionothermal and conventional synthesis via thermal condensation. Independent of chosen starting material, melem (triamino-s-heptazine) is initially formed from the starting material as the imminent precursor to poly(triazine imide). We elucidate the impact of various different carbon nitride precursor compounds on the formation process, propose a mechanism for the back reaction of heptazines to triazines, and rationalize the occurring processes.
Nitrogen-rich compounds: s-triazine and tri-s-triazine derivatives as high energy materials
Hanumantha Rao, Muddamarri,Ghule, Vikas D,Muralidharan, Krishnamurthi
, (2021)
Abstract: This article describes the syntheses, characterization, and energetic properties of 4, 6-diazido-N, N-dimethyl-1, 3, 5-triazin-2-amine and 2, 4, 6-tris (5-(3, 5-dinitrophenyl)-1H-tetrazol-1-yl)-1, 3, 5-triazine. Also, this paper emphasizes the i
Formation of a hydrogen-bonded heptazine framework by self-assembly of melem into a hexagonal channel structure
Makowski, Sophia J.,Koestler, Pia,Schnick, Wolfgang
, p. 3248 - 3257 (2012)
Self-assembly of melem C6N7(NH2) 3 in hot aqueous solution leads to the formation of hydrogen-bonded, hexagonal rosettes of melem units surrounding infinite channels with a diameter of 8.9 A. The channels are filled with strongly disordered water molecules, which are bound to the melem network through hydrogen bonds. Single-crystals of melem hydrate C6N7(NH2) 3·xH2O (x≈2.3) were obtained by hydrothermal treatment of melem at 200 °C and the crystal structure (R βar 3χ, a=2879.0(4), c=664.01(13) pm, V=4766.4(13)× 106 pm3, Z=18) was elucidated by single-crystal X-ray diffraction. With respect to the structural similarity to the well-known adduct between melamine and cyanuric acid, the composition of the obtained product was further analyzed by solid-state NMR spectroscopy. Hydrolysis of melem to cyameluric acid during syntheses at elevated temperatures could thus be ruled out. DTA/TG studies revealed that, during heating of melem hydrate, water molecules can be removed from the channels of the structure to a large extent. The solvent-free framework is stable up to 430 °C without transforming into the denser structure of anhydrous melem. Dehydrated melem hydrate was further characterized by solid-state NMR spectroscopy, powder X-ray diffraction, and sorption measurements to investigate structural changes induced by the removal of water from the channels. During dehydration, the hexagonal, layered arrangement of melem units is maintained whereas the formation of additional hydrogen bonds between melem entities requires the stacking mode of hexagonal layers to be altered. It is assumed that layers are shifted perpendicular to the direction of the channels, thereby making them inaccessible for guest molecules. Copyright
