<ref name=>Nicole E. Braml and Wolfgang Schnick (2012): "New Heptazine Based Materials with a Divalent Cation – Sr[H2C6N7O3]2·4H2O and Sr[HC6N7(NCN)3]·7H2O". ''Zeitschrift für anorganische und allgemeine Chemie'', volume 639, issue 2, pages ???

<!--
The new heptazine based compounds Sr[H2C6N7O3]2·4H2O and Sr[HC6N7(NCN)3]·7H2O have been synthesized by metathesis reactions in aqueous solution. Crystal structures were studied by single‐crystal X‐ray diffraction and Rietveld refinement. Strontium cyamelurate tetrahydrate exhibits distorted zigzag strands embedding Sr2+ ions surrounded by crystal water molecules (Fdd2, a = 1194.0(17), b = 6358.14(97), c = 602.73(89) pm, Z = 8, GOF = 1.034, Rp = 0.033, wRp = 0.042, RB = 0.84). Strontium melonate heptahydrate crystallizes in a layer‐like structure characteristic for heptazine‐based compounds (Pequation image, a = 660.76(13), b = 1080.7(2), c = 1353.8(3) pm, α = 101.67(3), β = 101.40(3), γ = 94.60(3)°, Z = 2, R1 = 0.032, wR2 = 0.072). Additionally, the thermal behavior has been studied by DTA/TG measurements and FTIR spectroscopy data are presented.-->

{{doi|10.1002/zaac.201200345}}
</ref>
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<ref name=>Hansjuergen Schroeder and Ehrenfried Kober (???): "Some Reactions of Cyameluric Chloride".

The Organics Division, Olin Mathieson Chemical Corporation, New Haven, Connecticut
Received May 23, (1962)
In contrast to the concept generally presented in the literature, cyameluric chloride was found to undergo nucleophilic
displacement reactions readily, and therefore was utilized as the starting material for the synthesis of various tri-s-triazine
derivatives. All three chlorine atoms can be easily replaced by means of sodium alkylates, phenols, or amines to give the
respective trialkylcyamelurates, triarylcyamelurates, and melem (triaminotri-s-triazine) derivatives. Difficulties were
encountered in the synthesis of unsymmetrical tri-s-triazines, since in most reactions cyameluric chloride trisubstitution predominated regardless of the ratio of the reactants. Only four unsymmetrical compounds could be obtained. A series of
triaryl tri-s-triazines was prepared by subjecting cyameluric chloride to a modified Friedel-Crafts reaction with benzene or
alkylbenzenes. While s-triazine derivatives show th

This invention relates to photographic silver halide emulsions containing dicarbocyanine dyes and in super sensitizing combination there with, hydromelonic acid, cyameluric acid, or an alkali metal salt thereof.
It is known in the art of making photographic emul
sions that certain dyes of the cyanine class alter the sensi tivity of photographic emulsions of the gelatino-silver halide kind, when the dyes are incorporated in the emul
sions. It is also known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the
sensitization of a given emulsion by a given dye may be
altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e., increasing the alkalinity) or both.
Thus, sensitization can be increased by bathing plates, coated with a spectrally sensitized emulsion, in water or in aqueous solutions of ammonia. Such a process of al tering the sensitivity of a sensitized emulsion by increasing the silver ion concentration and/or by decreasing the hydrogen ion concentration is commonly called "hyper sensitization'. Hypersensitized emulsions have generally poor keeping qualities. I have now found another means of altering the sensi tivity in emulsions containing dicarbocyanine dyes. Since
the conditions in the emulsion, i. e., the hydrogen ion
and/or the silver ion concentration undergo little or no
change in my method, I shall designate my method as a kind of supersensitization. It is, therefore, an object of my invention to provide photographic emulsions containing dicarbocyanine dyes and as supersensitizers therefor, certain derivatives of melon and cyameluric acid, particularly hydromelonic acid, cyameluric acid, or an alkali metal salt of these acids. Another object is to provide a means for prepar ing these supersensitized emulsions. Other objects will be
come apparent from a consideration of the following de scription and examples. While the derivatives of melon and cyameluric acid em ployed in my invention have been previously employed in photographic emulsions which have been optically sensi tized with “cyanine" and "merocyanine" dyes, the effects observed in the instant invention are not general. That
is, it has been found that no significant (or measureable) supersensitizing effect is observed with many simple cyanine and carbocyanine dyes. It was not expected, therefor, that the useful results illustrated below could be obtained with dicarbocyanine dyes. The dicarbocyanine dyes which are useful

</ref>
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<ref name=>Elisabeta Horvath-Bordon, Edwin Kroke, Ingrid Svoboda, Hartmut Fueß, Ralf Riedel, Sharma Neeraj and Anthony K. Cheetham (2004):

 issue 22,

''Dalton Transactions'',

Alkalicyamelurates, M3[C6N7O3]·xH2O, M = Li, Na, K, Rb, Cs: UV-luminescent and thermally very stable ionic tri-s-triazine derivatives†


<!--Cyamelurates are salts of cyameluric acid, a derivative of tri-s-triazine (1,3,4,6,7,9-hexaazacyclo[3.3.3]azine or s-heptazine). These compounds are thermally very stable and possess interesting structural and optical properties. Only very few tri-s-triazine derivatives have been reported in the literature. The water-soluble alkali cyamelurates were extensively characterized using NMR, FTIR, Raman, UV, luminescence spectroscopy and elemental analysis. In addition, the single crystal X-ray structure analyses of the four hydrates of lithium, sodium, potassium and rubidium cyamelurates (Li3[C6N7O3]·6H2O; Na3[C6N7O3]·4.5H2O; K3[C6N7O3]·3H2O; Rb3[C6N7O3]·3H2O) are presented. Thermogravimetric analysis shows that the dehydrated salts start to decompose at temperatures above 500 °C. The thermal stability does not depend on the cations which is in contrast to the analogous s-triazine salts, i.e. the alkali cyanurates M3[C3N3O3]. The photoluminescence spectra indicate a very strong solid state UV-emission with maxima between 280 and 400 nm.

Submitted
(2004) 13 Aug
Accepted
(2004) 04 Oct
First published
(2004) 25 Oct
DownloadCitation
(2004) Dalton Trans., 3900-3908

{{doi|10.1039/B412517G}}
</ref>
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<ref name=>

(2012) ''European Journal of Inorganic Chemistry'', volume , issue 11
 Full Access
Rare‐Earth Melonates LnC6N7(NCN)3·xH2O (Ln = La, Ce, Pr, Nd, Sm, Eu, Tb; x = 8–12): Synthesis, Crystal Structures, Thermal Behavior, and Photoluminescence Properties of Heptazine Salts with Trivalent Cations
Sophia J. Makowski Arne Schwarze Peter J. Schmidt Wolfgang Schnick

<!--The rare‐earth melonates LnC6N7(NCN)3·xH2O (Ln = La, Ce, Pr, Nd, Sm, Eu, Tb; x = 8–12) have been synthesized by metathesis reactions in aqueous solution and characterized by single‐crystal and powder XRD, FTIR spectroscopy, thermal analysis, and photoluminescence studies. Powder XRD patterns revealed isotypism of the La–Sm compounds. The structure of LaC6N7(NCN)3·8H2O has been solved and refined from single‐crystal diffraction data and those of the remaining salts have been refined from powder XRD data by Rietveld refinement. In the crystal structures, the melonate entities are arranged in corrugated layers, which alternate with layers of crystal water molecules. The lanthanide ions are coordinated by two melonate and six water molecules. LnC6N7(NCN)3·xH2O (Ln = Eu, Tb; x = 9–12) have also been investigated by photoluminescence studies. Neither hydrated nor dehydrated europium melonate exhibits luminescence under UV excitation, whereas photoluminescence studies of terbium melonate showed green emission with a maximum at 545 nm due to the 5D4→7F5 transition. Thermal analysis revealed rather low thermal stability of the rare‐earth melonates, which is probably due to the tight binding of crystal water that results in hydrolytic decomposition at elevated temperatures.

<!--New rare‐earth melonates LnC6N7(NCN)3·xH2O (Ln = La, Ce, Pr, Nd, Sm, Eu, Tb; x = 8–12) have been synthesized by metathesis reactions. In the crystal structures, melonate units and rare‐earth ions form 1D strands. The compounds were further characterized with respect to their thermal behavior and the luminescent properties of the europium and terbium salts.

{{doi|10.1002/ejic.201101251}}
</ref>
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<ref name=>

(2012) ''European Journal of Inorganic Chemistry'', volume , issue 6
 Full Access
Silver Melonates and Coordination Modes of the Multidentate [C6N7(NCN)3]3– Anion
Corinna Clauss Uwe Böhme Anke Schwarzer Edwin Kroke

<!--Three different silver melonates, Ag3[C6N7(NCN)3]·H2O (2a), Ag3[C6N7(NCN)3]·0.5NH3 (2b) and Ag3[C6N7(NCN)3]·2C2H8N2 (2c), and a nickel melonate, Ni3[C6N7(NCN)3]2·10NH3·6H2O (3), have been synthesised by the reaction of potassium melonate with silver nitrate either in an aqueous solution (2a), aqueous ammonia solution (2b) or an aqueous solution of ethylenediamine (2c) and with nickel nitrate in an aqueous ammonia solution (3). The crystal structure of 2c was determined by XRD [triclinic, Pequation image, a = 7.5499(4), b = 11.3438(6), c = 12.5741(7) Å, α = 72.138(4), β = 80.148(4), γ = 75.945(4)°, V = 984.90(9) Å3]. Silver atoms are coordinated to the terminal nitrogen atom of the cyanamide substituent as well as directly to the N atoms of the s‐heptazine core. Complex 2c crystallises in a layered structure. Adjacent Ag–melonate cation–anion units are connected by Ag–Ag interactions. The preferred coordination mode of metal ions at the melonate anion has been considered by quantum chemical calculations. Natural atomic charges calculated for the four nonequivalent, nucleophilic N atoms of the [C6N7(NCN)3]3– anion are (a) –0.596, (b) –0.619, (c) –0.675 and (d) –0.644. The metal coordination found experimentally in the melonates correlates with these relatively small charge differences and with the hard‐soft acid–base concept. However, (mono)protonation of the [C6N7(NCN)3]3– anion exclusively occurs at the terminal N atoms (b) of the s‐heptazine core, which is indicated experimentally and theoretically. Silver melonates 2a, 2b and 2c and nickel melonate 3 were further characterised by FTIR and 13C solid‐state magic‐angle spinning NMR spectroscopy, thermogravimetric/differential thermal analysis and elemental analysis. Solvent‐free complexes 2a and 2b, i.e. Ag3[C6N7(NCN)3], are thermally stable up to 500 °C. In contrast, 2c and 3 are thermally less stable.

<!--Silver melonates were synthesised, and their spectroscopic, structural and thermal properties were investigated. Theoretical and experimental data that concern the regioselective coordination of the trianion indicate that all four different terminal N atoms are able to interact with metal cations.

{{doi|10.1002/ejic.201101254}}
</ref>
----------------------------------------------------------------------
<ref name=>

(2011) volume 107,

''Annual Reports Section "A" (Inorganic Chemistry)'',

Alkaline and alkaline earth metals
Michael S. Hilla

<!--Advances in the coordination and inorganic chemistry of the elements of Groups 1 and 2 of the periodic table from the calendar year 2010 are summarised in this non-critical review. As was the case in previous years, coverage concentrates on topics centred around the synthesis, structures and applications of coordination compounds and the organometallic chemistry of these elements.

First published
(2011) 20 May
DownloadCitation
(2011) Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem., volume 107, pages 43-56

{{doi|10.1039/C1IC90016A}}
</ref>
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<ref name=>


Synthesis and Structure of 2,5,8-Triazido-s-Heptazine:  An Energetic and Luminescent Precursor to Nitrogen-Rich Carbon Nitrides
Dale R. MillerDale C. SwensonEdward G. Gillan
View Author Information
(2004) ''Journal of the American Chemical Society'', volume 126, issue  17, pages 5372-5373
(2004) 

(2004) Copyright © American Chemical Society

Derivatized s-triazine (C3N3) precursors have seen significant recent use in the production of carbon nitride materials. Larger polycyclic molecular precursors, such as those containing an s-heptazine core (C6N7 or tri-s-triazine), may improve stability and order in carbon nitride products. In this Communication, we describe the synthesis and crystal structure of 2,5,8-triazido-s-heptazine (2). Synthesis of 2 was achieved from melon, an oligomeric s-heptazine synthesized by the pyrolysis of NH4SCN. Melon was converted to molecular 2,5,8-trichloro-s-heptazine, which was then transformed to the triazide upon reaction with (CH3)3SiN3. The crystal structure of 2 verifies that the s-heptazine is planar and the azides adopt a pinwheel-like C3h arrangement around the periphery. The s-heptazine core shows π delocalization in the C−N bonds around the periphery (av. 1.33 Å), while the internal planar C−N bonds are longer (1.40 Å). The heptazine units pack into parallel, but offset, layered sheets in the crystal. The triazide 2 exhibits photoluminescence at 430 nm and rapidly and exothermically decomposes upon heating at 185 °C to produce a tan thermally stable carbon nitride powder with a formula near C3N4.

{{doi|10.1021/ja048939y}}
</ref>
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<ref name=>



Trimerization of NaC2N3 to Na3C6N9 in the Solid:  Ab Initio Crystal Structure Determination of Two Polymorphs of NaC2N3 and of Na3C6N9 from X-ray Powder Diffractometry
Barbara JürgensElisabeth IrranJulius SchneiderWolfgang Schnick
View Author Information
(2000) Inorg. Chem. , volume 39, issue  4, pages 665-670
(2000) 

(2000) Copyright © American Chemical Society


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Supporting Info (2)»Supporting Information
SUBJECTS:Crystal structureIonsPhysical and chemical processesParticulate matter
<!--Abstract Image
Sodium dicyanamide NaC2N3 was found to undergo two phase transitions. According to thermal analysis and temperature-dependent X-ray powder diffractometry, the transition of α-NaC2N3 (1a) to β-NaC2N3 (1b) occurs at 33 °C and is displacive. 1a crystallizes in the monoclinic system, space group P21/n (no. 14), with a = 647.7(1), b = 1494.8(3), c = 357.25(7) pm, β = 93.496(1)°, and Z = 4. The structure was solved from powder diffraction data (Cu Kα1, T = 22 °C) using direct methods and it was refined by the Rietveld method. The final agreement factors were wRp = 0.072, Rp = 0.053, and RF = 0.074. 1b crystallizes in the orthorhombic system, space group Pbnm (no. 62), with a = 650.15(5), b = 1495.1(2), c = 360.50(3) pm, and Z = 4. The structure was refined by the Rietveld method using the atomic coordinates of 1a as starting values (Mo Kα1, T = 150 °C). The final agreement factors were wRp = 0.044, Rp = 0.034, RF = 0.140. The crystal structures of both polymorphs contain sheets of Na+ and N(CN)2- ions which are in 1a nearly and in 1b exactly coplanar. Above 340 °C, 1b trimerizes in the solid to Na3C6N9 (2). 2 crystallizes in the monoclinic system, space group P21/n (no. 14), with a = 1104.82(1), b = 2338.06(3), c = 351.616(3) pm, β = 97.9132(9)°, and Z = 4. The structure was solved from synchrotron powder diffraction data (λ = 59.733 pm) using direct methods and it was refined by the Rietveld method. The final agreement factors were wRp = 0.080, Rp = 0.059, and RF = 0.080. The compound contains Na+ and the planar tricyanomelaminate C6N93-. The phase transition from 1b to 2 is reconstructive. It occurs in the solid-state without involvement of other phases or intermediates. The crystal structures of 1b and 2 indicate that there is no preorientation of the N(CN)2- in the solid before their trimerization to C6N93-.

{{doi|10.1021/ic991044f}}
</ref>
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<ref name=>

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Coordination Chemistry Reviews
(2013) volume 257, issues 13–14, July , pages 2032-2062
Coordination Chemistry Reviews
Review
Tri-s-triazines (s-heptazines)—From a “mystery molecule” to industrially relevant carbon nitride materials
AnkeSchwarzerTatyanaSaplinovaEdwinKroke

{{doi|10.1016/j.ccr.2012.12.006Get rights and content}}
<!--This review provides a comprehensive overview about the fascinating history and chemistry of s-heptazines in its ionic, molecular and polymeric forms – their synthesis, structure, properties and (potential) applications. The very stable aromatic s-heptazine (tri-s-triazine) C6N7 moiety has been discovered as early as in the 1830s, when Liebig, Berzelius and Gmelin independently synthesized the first s-heptazine derivatives. However, the correct tricyclic molecular structure was first proposed by L. Pauling about 100 years later. He obviously was intrigued by selected C6N7-derivatives until he died since the structure of a so-called “mystery molecule” C6N7(OH)2N3, which has not been synthesized so far, was later found on the chalkboard in his office. Very few s-heptazines including the parent molecule C6N7H3 (6) were synthesized and unambiguously analysed until the beginning of the 21st century. Due to the proposed ultrahardness of 3D carbon(IV) nitride networks C3N4 in the 1980/90s several researchers became interested in s-heptazines as precursors for novel carbon(IV) nitrides. Besides, in the patent literature numerous claims for the application of s-heptazines (and s-triazines C3N3X3) as flame retardants and for other applications are found. Thus, the formation, structure and properties of key molecular derivatives such as cyameluric chloride C6N7Cl3 (4), melem C6N7(NH2)3 (1), cyameluric acid C6N7(OH)3 (2), selected symmetric and asymmetric amides C6N7(NR1R2)3 − x(NR3R4)x, cyameluric esters C6N7(OR)3 and s-heptazine triazide C6N7(N3)3 (5) have been reported in recent years. In addition, various metal melonates M(I)3[C6N7(NCN)3], metal cyamelurates M(I)3[C6N7(O)3], s-heptazine-based metal-organic frameworks (MOFs) and melon [C6N7(NH2)(NH)]n were analysed in detail. Also, numerous reports on so-called carbon nitrides, which are in fact melon-related C/N/H-oligomers and polymers, have been reported recently. Although the structure of these materials is not known in detail, their properties as well as the properties of the above mentioned thoroughly analysed compounds provide a very promising outlook for various applications of carbon nitrides and C/N/H materials including s-heptazines, especially in the field of novel semiconducting materials, (photo)catalysts e.g. for hydrogen generation and carbon dioxide fixation, luminescent and in other ways optically active materials. Many of the latter characteristics have been investigated very recently and in most cases supported by experimental and theoretical studies.
</ref>
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<ref name=>

Chemistry – A European Journal volume 7, issue 24
 Full Access
Trimerization of Alkali Dicyanamides M[N(CN)2] and Formation of Tricyanomelaminates M3[C6N9] (M=K, Rb) in the Melt: Crystal Structure Determination of Three Polymorphs of K[N(CN)2], Two of Rb[N(CN)2], and One of K3[C6N9] and Rb3[C6N9] from X‐ray Powder Diffractometry
Elisabeth Irran Mag. Barbara Jürgens Dipl.‐Chem. Wolfgang Schnick

AbstractENTHIS LINK GOES TO A ENGLISH SECTIONDETHIS LINK GOES TO A KOREAN SECTION
The alkali dicyanamides M[N(CN)2] (M=K, Rb) were synthesized through ion exchange, and the corresponding tricyanomelaminates M3[C6N9] were obtained by heating the respective dicyanamides. The thermal behavior of the dicyanamides and their reaction to form the tricyanomelaminates were investigated by temperature‐dependent X‐ray powder diffractometry and thermoanalytical measurements. Potassium dicyanamide K[N(CN)2] was found to undergo four phase transitions: At 136 °C the low‐temperature modification α‐K[N(CN)2] transforms to β‐K[N(CN)2], and at 187 °C the latter transforms to the high‐temperature modification γ‐K[N(CN)2], which melts at 232 °C. Above 310 °C the dicyanamide ions [N(CN)2]− trimerize and the resulting tricyanomelaminate K3[C6N9] solidifies. Two modifications of rubidium dicyanamide have been identified: Even at −25 °C, the α form slowly transforms to β‐Rb[N(CN)2] within weeks. Rb[N(CN)2] has a melting point of 190 °C. Above 260 °C the dicyanamide ions [N(CN)2]− of the rubidium salt trimerize in the melt and the tricyanomelaminate Rb3[C6N9] solidifies. The crystal structures of all phases were determined by powder diffraction methods and were refined by the Rietveld method. α‐K[N(CN)2] (Pbcm, a=836.52(1), b=646.90(1), c=721.27(1) pm, Z=4), γ‐K[N(CN)2] (Pnma, a=855.40(3), b=387.80(1), c=1252.73(4) pm, Z=4), and β‐Rb[N(CN)2] (C2/c, a=1381.56(2), b=1000.02(1), c=1443.28(2) pm, β=116.8963(6)°, Z=16) represent new structure types. The crystal structure of β‐K[N(CN)2] (P21/n, a=726.92(1), b=1596.34(2), c=387.037(5) pm, β=111.8782(6)°, Z=4) is similar but not isotypic to the structure of α‐Na[N(CN)2]. α‐Rb[N(CN)2] (Pbcm, a=856.09(1), b=661.711(7), c=765.067(9) pm, Z=4) is isotypic with α‐K[N(CN)2]. The alkali dicyanamides contain the bent planar anion [N(CN)2]− of approximate symmetry C2v (average bond lengths: C−Nbridge 133, C−Nterm 113 pm; average angles N‐C‐N 170°, C‐N‐C 120°). K3[C6N9] (P21/c, a=373.82(1), b=1192.48(5), c=2500.4(1) pm, β=101.406(3)°, Z=4) and Rb3[C6N9] (P21/c, a=389.93(2), b=1226.06(6), c=2547.5(1) pm, β=98.741(5)°, Z=4) are isotypic and they contain the planar cyclic anion [C6N9]3−. Although structurally related, Na3[C6N9] is not isotypic with the tricyanomelaminates M3[C6N9] (M=K, Rb).

{{doi|10.1002/1521-3765(20011217)7:24<5372::AID-CHEM5372>3.0.CO;2-%23}}
</ref>
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<ref name=>



Structural Insights into Poly(Heptazine Imides): A Light-Storing Carbon Nitride Material for Dark Photocatalysis
Hendrik SchlombergJulia KrögerGökcen SavasciMaxwell W. TerbanSebastian BetteIgor MoudrakovskiViola DuppelFilip PodjaskiRenée SiegelJürgen SenkerRobert E. DinnebierChristian OchsenfeldBettina V. Lotsch*
(2019) Chem. Mater. , volume 31, issue  18, pages 7478-7486
(2019) 

(2019) Copyright © American Chemical Society

Authors ChoiceACS AuthorChoice
with CC-BY license
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Supporting Info (6)»Supporting Information
SUBJECTS:PotassiumLayersNitrogenInorganic carbon compounds
<!--Abstract Image
Solving the structure of carbon nitrides has been a long-standing challenge due to the low crystallinity and complex structures observed within this class of earth-abundant photocatalysts. Herein, we report on two-dimensional layered potassium poly(heptazine imide) (K-PHI) and its proton-exchanged counterpart (H-PHI), obtained by ionothermal synthesis using a molecular precursor route. We present a comprehensive analysis of the in-plane and three-dimensional structure of PHI. Transmission electron microscopy and solid-state NMR spectroscopy, supported by quantum-chemical calculations, suggest a planar, imide-bridged heptazine backbone with trigonal symmetry in both K-PHI and H-PHI, whereas pair distribution function analyses and X-ray powder diffraction using recursive-like simulations of planar defects point to a structure-directing function of the pore content. While the out-of-plane structure of K-PHI exhibits a unidirectional layer offset, mediated by hydrated potassium ions, H-PHI is characterized by a high degree of stacking faults due to the weaker structure directing influence of pore water. Structure–property relationships in PHI reveal that a loss of in-plane coherence, materializing in smaller lateral platelet dimensions and increased terminal cyanamide groups, correlates with improved photocatalytic performance. Size-optimized H-PHI is highly active toward photocatalytic hydrogen evolution, with a rate of 3363 μmol/gh H2 placing it on par with the most active carbon nitrides. K- and H-PHI adopt a uniquely long-lived photoreduced polaronic state in which light-induced electrons are stored for more than 6 h in the dark and released upon addition of a Pt cocatalyst. This work highlights the importance of structure–property relationships in carbon nitrides for the rational design of highly active hydrogen evolution photocatalysts.

{{doi|10.1021/acs.chemmater.9b02199}}
</ref>
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<ref name=>

UNICAMP - Univ Estadual de Campinas
''Chemistry Europe''

Chemistry – A European Journal volume 13, issue 4
 Full Access
The Tautomeric Forms of Cyameluric Acid Derivatives†
Nadia E. A. El‐Gamel Dr. Lena Seyfarth Jörg Wagler Dr. Helmut Ehrenberg Dr. Marcus Schwarz Dr. Jürgen Senker Prof. Dr. Edwin Kroke Prof. Dr.

† Tri‐s‐triazine derivatives, Part 4. For part 3 see ref.  25.

<!--The tautomerism of cyameluric acid C6N7O3H3 (1 a), cyamelurates and other heptazine derivatives has recently been studied by several theoretical investigations. In this experimental study we prepared stannyl and silyl derivatives of cyameluric acid (1 a): C6N7O3[Sn(C4H9)3]3 (3 a), C6N7O3[Sn(C2H5)3]3 (3 b), and C6N7O3[Si(CH3)3]3 (4). In order to investigate the structure of 1 a the mono‐ and dipotassium cyamelurate hydrates K(C6N7O3H2)⋅2 H2O (5) and K2(C6N7O3H)⋅1 H2O (6) were synthesized by UV/Vis‐controlled titration of a potassium cyamelurate solution with aqueous hydrochloric acid. Compounds 3–6 were characterized by FTIR and solid‐state NMR spectroscopy as well as simultaneous thermal analysis (TGA, DTA). The single crystal X‐ray structures of the salts 5 and 6 show that the hydrogen atoms in both anions are localized on the peripheral nitrogen atoms. This indicates—in combination with the solid‐state NMR studies—that the most stable tautomer of solid 1 a is the triketo form with C3h symmetry. However, derivatives of both the hydroxyl and the amido tautomers may be formed depending on the substituent atoms: The spectroscopic data and single crystal structures of compounds C6N7O3[Si(CH3)3]3 (4) and the solvate C6N7O3[Sn(C2H5)3]3⋅C2H4Cl2 (3 b′) show that the former is derived from the symmetric trihydroxy form of 1 a, while 3 b′ crystallizes as a chain‐like polymer, which contains the tin atoms as multifunctional building blocks, that is, bridging pentacoordinated Et3SnO2 and Et3SnON units as well as non‐bridging four‐coordinated Et3SnN units. The cyameluric nucleus is part of the polymeric chains of C6N7O3[Sn(C2H5)3]3⋅C2H4Cl2 (3 b′), by the action of both tautomeric forms of cyameluric acid, the amide and the ester form.

{{doi|10.1002/chem.200600435}}
</ref>
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<ref name=>

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CHEMICAL PROPERTIES AND MOLECULAR STRUCTURE OF DERIVATIVES OF sym-HEPTAZINE [1,3,4,6,7,9,9b-HEPTAAZAPHENALENE, TRI-1,3,5-TRIAZINE]
A I Finkel'shtein and N V Spiridonova

Published 31 July (1964) • ©, (1964) The Chemical Society
Russian Chemical Reviews, volume 33, Number 7
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<!--CONTENTS

I. Introduction 400

II. Does melam exist? 400

III. Melem 401

IV. Melon — the material of Pharoah's serpents 402

V. Cyameluric acid, its salts and amides 403

VI. Hydromelonic acid 404

VII. Other derivatives of sym-heptazine 404
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Journal of Macromolecular Science, Part B
Physics
(2008) volume 47, - issue 5
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Original Articles
Effect of Metallic Salts of Malonic Acid on the Formation of β Crystalline Form in Isotactic Polypropylene
Qiang Dou,Qu-Liang Lu  and Huai-Dong Li
(2008) pages 900-912 | Received 22 Mar 2008, Accepted 10 Apr 2008, Published online: 26 Aug

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Introduction
Experimental
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<!--The effects of malonic acid and the lithium, sodium, potassium, zinc, magnesium, calcium, strontium, and barium salts of malonic acid on the formation of β crystalline form in isotactic polypropylene at the crystallization temperatures 120 and 130°C have been investigated. It was found that malonic acid and the lithium, sodium, and potassium salts of malonic acid inhibit the formation of β crystalline form in polypropylene. Zinc malonate has a limited positive effect on the formation of β crystalline form, while magnesium, calcium, strontium, and barium salts are β nucleating agents, in descending order. The decreased β nucleation abilities of the alkaline earth metallic salts of malonic acid are attributed to the increasing atomic radii of the combined metals and decreasing crystallization temperatures

{{doi|10.1080/00222340802216053}}
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Fluorinated sym.-triazine derivatives
Classifications
 C06B43/00 Compositions characterised by explosive or thermic constituents not provided for in groups C06B25/00 - C06B41/00
View 1 more classifications
US3515603A
United States

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InventorHarvey A BrownJohn G EricksonDonald R HustedCharles D WrightCurrent Assignee 3M Co
Worldwide applications
(1962) US
Application US243179A events
(1962)-12-03
Application filed by 3M Co
(1962)-12-03
Priority to US24317962A
(1970)-06-02
Application granted
(1970)-06-02
Publication of US3515603A
(1987)-06-02
Anticipated expiration
Status
Expired - Lifetime

A number of synthetic pyrolytic methods which are known
to the art lead to the formation of a complex material known as melon which is believed to comprise, inter alia, condensed derivatives of tri-s-triazine. The components of
this mixture, like melem, are insoluble and melon is thus
an unresolvable mixture including substances such as those represented

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(2009) ,

''Journal of Materials Chemistry'',

Corrugated layered heptazine-based carbon nitride: the lowest energy modifications of C3N4 ground state†
J. Gracia*abc and P. Krollab

<!--We systematically investigate trends in carbon nitride structures targeting the lowest energy configuration of C3N4. Layered conformations, sp2-bonded, turn out to be more favorable than denser, sp3-bonded, networks. Among layered structures, those comprising the heptazine motif are consistently lower in energy when compared to triazine-based models. Additional decrease of energy is achieved by corrugation of the layers, driven by avoiding repulsive interactions between nitrogen lone-pairs. Consequences of such curvature are for one the necessity to approximate the lowest energy configuration of C3N4 with very large unit cells, as indicated through ab-initio molecular dynamic simulations. Secondly, curvature favors the genesis of confined structures of carbon nitride: the energy difference between “one-dimensional” nanostructures and the layered state is at least smaller for C3N4 than for pure carbon.

Correction
HTM (3K)
Article information

Submitted
(2008) 01 Dec
Accepted
(2009) 12 Feb
First published
(2009) 17 Mar
DownloadCitation
(2009) J. Mater. Chem.,  volume 19, issue 19, pages 3013-3019

{{doi|10.1039/B821568E}}
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