Triclinic ammonium hydrogen succinate compound (space group
P
1
-
) is known to present very short O–H⋅⋅⋅O hydrogen bonds in association with a second-order phase transition around 170 K. Whatever ...the temperature, its crystal structure is characterized by a statistical distribution of the hydrogen atom belonging to the hydrogen succinate molecule on two crystallographic sites, leading to a disordered structure. In this study, we report on the crystal structure of a new ordered structural form of the title compound NH
4
HC
4
H
4
O
4
, determined by single-crystal X-ray diffraction at room temperature. This new ordered form crystallizes in the triclinic space group
P
1
-
with refined cell parameters:
a
= 6.4868(16) Å,
b
= 7.4313(17) Å,
c
= 7.4339(17) Å, α = 112.058(8)°, β = 96.477(9)°, γ = 109.026(8)° and
V
= 302.45(12) Å
3
. Hydrogen succinate molecules are in
trans
conformation in the ordered form and in
gauche
conformation in the disordered one. It leads to different molecular assemblies of the ammonium cations and hydrogen succinate anions, and consequently, to different hydrogen bond networks. The crystal structure stability of this new ordered structural form is discussed and compared to that of the disordered form.
Graphical Abstract
Single crystals of a new ordered form of ammonium hydrogen succinate NH
4
HC
4
H
4
O
4
were grown from water solution of ammonium thiosulfate (NH
4
)
2
S
2
O
3
and succinic acid C
4
H
6
O
4
. The crystal structure determination reveals different molecular assembly and hydrogen bond network in the ordered form compared to those encountered in the previously reported disordered form. The crystal structure of this ordered form is discussed and compared to that of the disordered form.
At the occasion of the fiftieth birthday of the introduction of the term ‘metal atom cluster’ by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the ...engineering of molecular assemblies and nanomaterials based on octahedral Re
6
metal atom clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic–inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped
Re
6
Y
8
i
Y
6
a
cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form
Re
6
Y
8
i
L
6
a
(L = CN, OH, various organic ligands…). This work reports advances in the synthesis of
Re
6
Y
8
i
Y
6
a
and
Re
6
Y
8
i
L
6
a
cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions.
We report the photoluminescence (PL) and cathodoluminescence (CL) properties of face-capped Mo
6
X
i
8
L
a
6
2−
(X = Cl, Br, I; L = organic or inorganic ligands) cluster units. We show that the ...emission of Mo
6
metal atom clusters depends not only on the nature of X and L ligands bound to the cluster and counter-cations, but also on the excitation source. Seven members of the A
x
Mo
6
X
i
8
L
a
6
series (A = Cs
+
, (n-C
4
H
9
)
4
N
+
, NH
4
+
) were selected to evaluate the influence of counter-cations and ligands on de-excitation mechanisms responsible for multicomponent emission of cluster units. This study evaluates the ageing of each member of the series, which is crucial for further energy conversion applications (photovoltaic, lighting, water splitting, etc.).
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