An asymmetric twistacene, 1′,4′‐diphenyl‐naphtho‐(2′.3′:1.2)‐pyrene‐6′‐nitro‐7′‐methyl carboxylate (tetracene 2), was synthesized by using benzyne‐trapping chemistry. Its structure, determined by ...X‐ray crystallography, confirmed that this material has a twisted topology with torsion angles as high as 23.8(3)°. Organic light‐emitting devices using tetracene 2 as either charge‐transporting materials or emitters have been fabricated. The results indicate that this material has bipolar transporting behavior in these devices.
An asymmetric twistacene, 1′,4′‐diphenyl‐naphtho‐(2′.3′:1.2)‐pyrene‐6′‐nitro‐7′‐methyl carboxylate (tetracene 1, see graphic), was synthesized by using benzyne‐trapping chemistry. Its structure confirmed that this material has a twisted topology with torsion angles as high as 23.8(3)°. Organic light‐emitting devices with tetracene 1 as either charge‐transporting materials or emitters have been fabricated.
This study delves into the intriguing realm of chalcogen-bonding interactions, specifically focusing on tellurium(
ii
) and/or tellurium(
iv
) interactions with iodide species within six crystals. ...Utilising comprehensive computational chemistry calculations and underpinned by crystallographic data retrieved from the Cambridge Structural Database, this research elucidates the supramolecular aggregation, bonding nature and interaction energetics of Te I non-covalent bonds in a series of crystals containing each of tellurium(
ii
), tellurium(
iv
) and iodide. The investigation encompasses a variety of molecular assemblies, ranging from zero-dimensional to complex three-dimensional architectures. Tellurium(
ii
) atoms formed Te I interactions in six of the crystals but tellurium(
iv
) participated in Te I interactions in only three crystals despite there being equal numbers of tellurium(
ii
) and tellurium(
iv
) atoms in the zero- and one-dimensional assemblies. Several computational tools, including Molecular Electrostatic Potential (MEP) surfaces, Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses, provide a nuanced understanding of the electron density topology and charge transfer mechanisms. In some assemblies, where the Te I interactions are ∼3.2 Å, the interaction energies are very large,
i.e.
25.6 to 38.8 kcal mol
−1
, suggesting partial covalent character, an observation corroborated by the NBO analysis; longer Te I separations correlate with reduced energies,
i.e.
3.1 to 7.0 kcal mol
−1
. Crucially, it is noteworthy that the Te I interactions identified in this study are distinctly characterised as chalcogen bonds, rather than halogen bonds.
The importance of σ-hole bonding is emphasised in a series of mixed tellurium(
ii
)/tellurium(
iv
)/iodide crystals.
•Heavy element compounds offer distinct possibilities for directed self-assembly.•Secondary bonding, e.g. tetrel, pnictogen and chalcogen bonding, is reviewed.•Metal⋯metal interactions can be ...exploited to assemble molecules via relativistic effects.•Metal(lone-pair) contacts are found for main group element compounds.•Chelate rings can function in ways similar to their organic counterparts.
An overview of supramolecular assembly sustained by intermolecular contacts pertinent to the coordination chemistry community is presented. Herein, the supramolecular architectures sustained by secondary bonding, encompassing tetrel, pnictogen and chalcogen bonding, interactions occurring between metal centres, metal⋯hydrogen, metal⋯π, main group element(lone pair)⋯π, and finally, those involving chelate rings sustained by formal bonding or by hydrogen bonding are described. Whenever possible, comments are included on the nature of the intermolecular interactions and information on the energy of stabilisation they impart. A wide range of intermolecular connectivities are applicable to heavy element compounds and these complement the more established hydrogen bonding and halogen bonding. Interestingly, the energies associated with “emerging” intermolecular interactions often approach those of conventional intermolecular interactions suggesting these may be competitive in directing the way molecules assemble in the condensed phase.
The Cambridge Structural Database was surveyed for crystals featuring Hg S secondary-bonding interactions for mercury(
ii
) compounds (excluding organomercury compounds). In all, 43 examples of ...crystals including intermolecular Hg S interactions operating largely in isolation from other directional interactions were detected with the Hg S interactions within zero-, one- and two-dimensional aggregation patterns. Over 50% of the aggregates are one-dimensional with topologies ranging from linear, zigzag and helical chains, and ribbons to tapes; 30% of the crystals exhibit zero-dimensional aggregates. Crucially, selected examples were subjected to DFT calculations with mapping of the molecular electrostatic potentials (MEPs) of the molecules as well as quantum theory of atoms in molecules (QTAIM), non-covalent interaction plot (NCIPLOT) and natural bond order (NBO) investigations. This study confirms the presence of σ-/π-holes or positive belts at the mercury atom depending on the coordination geometry, defined by covalently and non-covalently bound donor atoms. In molecules coordinated by sulphur donors, the σ-hole at the sulphur atom merges with the positive belt around the mercury atoms, assisting in the formation of spodium bonds and providing higher directionality. The QTAIM/NCIPLOT analysis supports both the existence and non-covalent nature of the spodium bonds. Finally, the NBO analysis reveals charge transfer effects indicating the existence of LP → σ* orbital interactions in the studied molecules; LP is a lone-pair. The energy of stabilisation provided by spodium bonds ranges from a low 3 kcal mol
−1
to a high 19 kcal mol
−1
,
i.e.
values often greater than those by conventional hydrogen-bonding interactions.
A CSD survey reveals the presence of Hg S interactions within zero-, one- and two-dimensional aggregation patterns in non-organomercury crystals. Theory confirms the stabilising nature of σ-/π-holes or positive belts formed at the mercury atom.
The Cambridge Structural Database has been surveyed for crystals featuring organo-Hg···S secondary-bonding interactions within supramolecular aggregates. Nearly 50% of crystals where Hg···S ...interactions could potentially form, featured Hg···S contacts within zero- or one-dimensional supramolecular assemblies with only a few examples of two-dimensional arrays featuring Hg···S interactions. This high propensity of Hg···S contact formation reflects the inherent thiophilic nature of mercury but also the relatively open access to mercury owing to the linear C–Hg–S coordination geometries, the prevalence of close intramolecular Hg···S, Hg···O and Hg···N interactions notwithstanding.
The 1:1:1 binary co-crystal solvates formulated as 2,2′-dithiodibenzoic acid (DTBA), 4-halobenzoic acid (4-
X
BA) and dimethylformamide (DMF) for X = Cl (
1
), Br (
2
) and I (
3
) are isomorphous ...and the supramolecular association in this series has been probed by a wide range of computational chemistry techniques. The common feature of the molecular packing is the formation of robust three-molecule aggregates sustained by a non-symmetric { HOC&z.dbd;O}
2
synthon, formed between DTBA and 4-
X
BA, and a DTBA-hydroxyl-O-H O(carbonyl-DMF) hydrogen bond (with a reciprocating DMF-C-H O(carbonyl-DTBA) contact). Supramolecular tapes are evident and feature DTBA-C-H O(DMF), DTBA-C-H S(DTBA), DMF-O π(DTBA-phenyl) and DMF-C-H π(DTBA-phenyl) contacts. The point-to-point connections between the tapes are of the type π(4-
X
BA-phenyl) π(DTBA-phenyl), π(4-
X
BA-phenyl) π(4-
X
BA-phenyl), DTBA-C-H π(DTBA-phenyl) and DMF-C X tetrel bonding. However, a difference is noted here between
1
and
2
, and
3
, in that the DTBA-C-H π(DTBA-phenyl) contacts are beyond standard separations, a feature of the packing that is traced directly to the influence of the iodide atom as opposed to the lighter congeners. There are systematic increases in the
b
and
c
unit-cell lengths correlating with the size of the halide, and in the case of
3
this expansion diminishes the influence of the DMF-C-H π(DTBA-phenyl) contact as the tapes are pushed apart. This contact along the
a
-direction in
3
is replaced by DMF-H O(DTBA-carbonyl) and DTBA-C-H S(DTBA) contacts. Additional attractive interactions along the
a
-axis include C-X quasi-π{ HOC&z.dbd;O}
2
bonding interactions which are at a maximum strength in
3
(
ca.
5.0 kJ mol
−1
) and contribute to the shortening of the
a
-axis in the order
3
<
2
<
1
.
The enhanced steric and bonding influences exerted by iodide are not sufficient to perturb isostructurality in a series of ternary crystals that differ only in the halide substituent,
i.e.
X = Cl, Br and I.
A convenient method for the synthesis of
N
3
,
N
4
-disubstituted 3,4-diaminopyrazolo3,4-
d
pyrimidines was developed using a three-component reaction of 3,5-diaminopyrazole-4-carbonitriles with ...primary amines and orthoesters. The preparation of 116 examples demonstrated the good scope of the reaction, which tolerated variations in the substrate structure and was particularly efficient under microwave irradiation. The short reaction time and chromatography-free product isolation add practicality to this method. The anti-leukemic activity was assessed
in vitro
using K562 and Jurkat T cells, and the selectivity of the most active compounds was evaluated using non-cancerous MRC5 cells. The most promising compound inhibited Jurkat T cells with a GI
50
value of 0.5 μM and a selectivity index of 65.
A one-pot multicomponent microwave-assisted synthesis was developed for the synthesis of pyrazolo3,4-
d
pyrimidines isosteric to adenine. Some compounds were identified as potent and selective anti-leukemic agents.
Crystal structures of transition and main group element 1,1-dithiolates are shown to be partially sustained by C-H···π(chelate) interactions. For the planar binary bisdithiocarbamates, ...C-H···π(MS(2)C) interactions lead to aggregation patterns ranging from a 0-D four molecule aggregate to a 3-D architecture but with the majority of structures featuring 1-D or 2-D supramolecular assemblies.
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