Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
melon were prepared according to literature (see below). Lithium
Keywords: Carbon nitrides; Layered compounds; Ionother-
mal synthesis; Reaction mechanisms; Heterocycles
chloride (pure) was purchased from AppliChem, lithium bromide
(98%) was purchased from Fluka, potassium chloride (99.5%) and
potassium bromide were purchased from Merck Chemicals GmbH.
Preparation of Melam: Melam was prepared in a two-step synthesis
via melamium chloride ammonium chloride.[27,41] Melamine (365 mg,
2.90 mmol) and ammonium chloride (83 mg, 1.56 mmol) were ground
together and sealed in a glass ampoule (length 120 mm, inner diameter
11 mm). The ampoule was heated to 723 K in a vertical tube furnace
with a rate of 1 K·min–1, held at this temperature for 12 h and cooled to
room temperature with 6 K·min–1. The melamium chloride ammonium
chloride adduct sublimed at the upper end of the ampoule was stirred
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Preparation of Melem: Melamine (30.09 g, 239 mmol) in a porcelain
crucible covered with a lid was placed in a muffle furnace pre-heated
to 473 K and heated to 673 K with 10 K·min–1. It was held at this
temperature for 24 h and then cooled to room temperature at
10 K·min–1. The product was ground with mortar and pistil and ex-
posed to the identical temperature program again. Melem was obtained
as a pale beige powder. The product was identified by FTIR spec-
troscopy and powder X-ray diffractometry.
Preparation of Melon: Melamine (37.82 g, 300 mmol) in a porcelain
crucible covered with a lid was placed in a muffle furnace pre-heated
to 473 K and heated to 773 K with 10 K·min–1. It was held at this
temperature for 24 h and then cooled to room temperature at
10 K min–1. The product was ground with mortar and pistil and ex-
posed to the identical temperature program again. Melon was obtained
as a yellow powder. The product was identified by FT-IR spectroscopy
and powder X-ray diffractometry.
Synthesis of PTI/Li+Cl–: Carbon nitride precursor material (100 mg)
was ground together with 500 mg of a eutectic salt mixture, either LiCl
(226 mg, 5.44 mmol) and KCl (274 mg, 3.67 mmol) or LiBr (239 mg,
2.75 mmol) and KBr (261 mg, 2.19 mmol), and sealed in silica glass
ampoules (length 120 mm, inner diameter 11 mm). Amounts of salt
were chosen well in excess as described in literature.[10,14] Following
these protocols, identical weights of chloride melt and bromide melt
instead of identical amounts of substance were used for practical
reasons, since no significant influence was expected. The ampoules
were placed in a vertical tube furnace pre-heated to 773 K and kept
there for either 5 min, 10 min, 20 min, 30 min, 120 min, or 720 min.
Afterwards, the ampoule was removed from the hot oven and the reac-
tion quenched by submerging in an ice-water mixture. The reaction
product was isolated and identified by FT-IR spectroscopy and powder
X-ray diffractometry.
General Techniques: FT-IR spectra were recorded with a Perkin–El-
mer BX II FTIR spectrometer equipped with a DuraSampler Diamond
ATR (attenuated total reflection) unit. Measurements were conducted
at room temperature under exposure to air. Powder X-ray diffracto-
grams were recorded with a Huber Imaging Plate Guinier Dif-
fractometer G670 (guinier geometry, Cu-Kα1 radiation, λ = 1.5406 Å)
equipped with a CCD camera and an oscillating flat specimen holder.
Acknowledgements
Financial support granted by the Fonds der Chemischen Industrie
(FCI) and the Deutsche Forschungsgemeinschaft (DFG) is gratefully
acknowledged.
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