Latticial metal complex or grid complex is a
supramolecular complex of several metal atoms and coordinating
ligand
In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
s which form a grid-like structural motif. The structure formation usually occurs while on thermodynamic
molecular self-assembly. They have properties that make them interesting for information technology as the future storage materials.
[J.-M. Lehn et al., Angew. Chem., 2004, 116, S. 3728–3747.]
Chelate ligands are used as ligands in
tetrahedral
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...
or
octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...
structures, which mostly use nitrogen atoms in
pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a ...
like ring systems other than donor centers. Suitable metal ions are in accordance with octahedral coordinating transition metal ions such as Mn or rare tetrahedral Coordinating such as Ag used.
Nomenclature
The nomenclature is based on
× mG, n corresponds to the number of ligands above the metal ion level, m the number below ones. In case of using only one ligand type, the homoleptic grid is formed in a square
xnstructure. When using different ligands arise
heteroleptic
In inorganic chemistry, a homoleptic chemical compound is a metal compound with all ligands identical. The term uses the " homo-" prefix to indicate that something is the same for all. Any metal species which has more than one type of ligand is he ...
complexes, however, compete with the
homoleptic
In inorganic chemistry, a homoleptic chemical compound is a metal compound with all ligands identical. The term uses the " homo-" prefix to indicate that something is the same for all. Any metal species which has more than one type of ligand is he ...
. The number of metal ions is always n + m.
Application
The grid complexes exhibit
pH-dependent changes in the
optical absorption
In physics, absorption of electromagnetic radiation is how matter (typically electrons bound in atoms) takes up a photon's energy — and so transforms electromagnetic energy into internal energy of the absorber (for example, thermal energy). ...
, electronic spin states and reversible redox states. The latticial metal complexes may thus be used theoretically for information storage and processing in the future.
Other Uses
An interwoven grid complex has been used to template the synthesis of a doubly-twisted
atenane (otherwise known as a
Solomon Link). The unique arrangement of interwoven ligands around the planar array of iron, zinc, or cobalt ions generated the crossing points required to covalently trap the interlocked structure using ring-closing metathesis. Building on this discovery, 2 × 2 interwoven grids were used to template the synthesis of more topologically complex molecules: a six-crossing doubly-interlocked
atenane and a granny knot. In 2021, the first report of a 3 × 3 interwoven grid was published. It was used to template the synthesis of a molecular
Endless Knot
Endless knot in a Burmese Pali manuscript
The endless knot or eternal knot is a symbolic knot and one of the Eight Auspicious Symbols. It is an important symbol in Hinduism, Jainism and Buddhism. It is an important cultural marker in place ...
.
References
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Coordination chemistry
Supramolecular chemistry
Chemical structures