Graphitic carbon nitride C6N9H3·HCl: Characterisation by UV and near-IR FT Raman spectroscopy

Pharaoh's Serpents: New Insights into a Classic Carbon Nitride Material

“…It has been argued that the UV excitation results in observation of highly localized structures within the amorphous material due to a combination of electronic and optical effects. [37] The overall form of the spectrum is similar to that observed for the polymeric C x N y H z compound that has a heptazine-based structure. However, the distinctive features at 980 and 690 cm -1 have also been associated with symmetric stretching motions of independent C 3 N 3 rings within polytriazine imide structures.…”

Tuning of gallery heights in a crystalline 2D carbon nitride network

“…24,25 Inorganic salt melts have also been utilised for the synthesis of extended, covalently bonded, organic frameworks. 15,[26][27][28][29] The use of eutectic salt melts as both solvent and structure-directing agent in the polycondensation and deamination reaction of dicyandiamide leads to the formation of a graphitic (C, N) material, 30 31,33,34 This is due in part to inhomogeneous distribution of halides and introduction of vacancies in the interstitial space brought about by the washing procedure.…”

Carbon nitrides: synthesis and characterization of a new class of functional materials

“…18. 25,64 The broad band at 3024 cm À1 is consistent with N-H stretching of the imido units bridging between the triazine rings, whereas that at 2778 cm À1 was suggested to arise from the protonated triazine rings that are introduced to compensate for the Cl À ions located within the intralayer (C 12 N 12 ) void sites. The unusually low N-H stretching frequency was thought to arise from H-bonding to the N site on an adjacent heterocycle, or perhaps by interaction with the Cl À ions located within the C 12 N 12 layer voids.…”

“…However, for more condensed gCN materials, the Raman data become dominated by solid state excitation and resonance effects, including electron-phonon coupling. 64 Jürgens et al 58 reported Raman data for the molecular crystal melem using near-IR (1064 nm) laser irradiation and Fourier transform (FT) acquisition techniques. Quirico et al also recorded Raman spectra for polymeric C x N y H z compounds prepared by gas phase reactions as models for the atmospheric ''tholins'' of Titan, as well as melamine, s-triazine and PTIÁHCl, using UV (244, 229 nm) as well as near-IR (1064 nm) excitation (Fig.…”

“…That result was interpreted in terms of loss of phonon coherence and spectral broadening for longer excitation wavelengths that probed more extended vibrational states, compared with more localized vibrational modes observed using UV excitation. 64 Although Raman scattering is commonly used to complement IR spectroscopy in structural analysis studies of molecular compounds and solid state materials, the fact that electronic transitions associated with both localized and extended states occur throughout the visible range for gCN compounds and enter into resonance with exciting laser wavelengths means that interpretation of the data is more subtle rather than simply giving information on the molecular structure. As we begin to better understand the optoelectronic properties of gCN materials, the Raman data will help us develop better control and optimization of functional properties related to light harvesting, luminescence and photocatalysis, as well as optically assisted routes to synthesis and functionalization.…”