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Crystalline cluster materials, a class of functional motif aggregations, provide a great opportunity for tuning the properties stemming from the flexible and accurate variation of inorganic and organic compositions. In this study, we demonstrate the effects of functional ligand and ring size regulation on the structures and third‐order nonlinear optical (NLO) properties. Revealed by the single‐crystal X‐ray analysis results, aluminum molecular ring expansion is achieved by 2×9 and 3×6 strategies. In terms of the given organic shells, we further tuned the aluminum molecular ring sizes from 3.0 nm to 1.7 nm. The picosecond Z‐scan measurements results revealed that the third‐order NLO performances do not only depend on the general conjugate interactions but are also related to hydrogen bonding, polarizability, and ring sizes. The large nonlinear absorption coefficient and onset prove that the observed samples are promising candidates for the field of nonlinear optics. [ABSTRACT FROM AUTHOR]

Although numerous adsorbent materials have been reported for the capture of radioactive iodine, there is still demand for new absorbents that are economically viable and can be prepared by reliable synthetic protocols. Herein, we report a coordination‐driven self‐assembly strategy towards adsorbents for the sequential confinement of iodine molecules. These adsorbents are versatile heterometallic frameworks constructed from aluminum molecular rings of varying size, flexible copper ions, and conjugated carboxylate ligands. Additionally, these materials can quickly remove iodine from cyclohexane solutions with a high removal rate (98.8 %) and considerable loading capacity (555.06 mg g−1). These heterometallic frameworks provided distinct pore sizes and binding sites for iodine molecules, and the sequential confinement of iodine molecules was supported by crystallographic data. This work not only sets up a bridge between molecular rings and infinite porous networks but also reveals molecular details for the underlying host–guest binding interactions at crystallographic resolution. [ABSTRACT FROM AUTHOR]

Presented herein are the AlIII molecular ring architectures from 8‐ring to 16‐ring. Although there are numerous reported cyclic coordination compounds based on transition metals, gallium, or lanthanides, the Al versions are less developed due to the fast hydrolysis nature of Al3+ ion. With the assistant of monohydric alcohols, a series of atomic precisely Al molecular rings based on benzoates are synthesized. The ring expansion of these Al‐rings from 8‐ring to 16‐ring is related to the monohydric alcohol structure‐directing agents. Moreover, the organic ligands on the Al‐rings can be modified by using various benzoate derivatives, which lead to tunable surface properties of the Al‐rings from hydrophilicity to ultra‐hydrophobicity. Importantly, 4‐aminobenzoic acid bridged 16‐ring is soluble in organic solvents and exhibits high solution stability revealed by mass spectroscopy. Ligand substitution also can be performed between these Al‐rings, which reveal controllable ligand functionalization of these Al‐rings. [ABSTRACT FROM AUTHOR]

Varying the polyethyleneglycol spacer between two (iso)-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some cases. These structures can be tuned by careful design of the ligand, the use of solvent and the counter ions, influencing also other important properties such as light stability and solubility. The latter is important in the context of biomedical applications, using silver compounds as antimicrobial agents.

The electric current of $$Cr_8$$ and $$Cr_7Ni$$ molecular rings with two semi-infinite, $$Au$$ leads have been investigated. We have performed numerical calculations using the non-equilibrium Green's function method combined with the density functional theory. Then the electric current under a given applied bias voltage has been obtained in a two terminal molecular circuit system. Transport characteristics of these molecular-based quantum rings and coherent transport features of the system have been studied. It was shown that negative differential conductance regime arises, in several ranges of the bias voltage. [ABSTRACT FROM AUTHOR]

A series of self-assembled 'double saddle'-type trinuclear complexes of [Pd3L′3 L2] formulation have been synthesized by complexation of a series of cis-protected palladium(II) components with a slightly divergent 'E-shaped' non-chelating tridentate ligand, 1,1′-(pyridine-3,5-diyl)bis(3-(pyridin-3-yl)urea ( L). The cis-protecting agents L′ employed in the study are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), for 1, 2, 3, and 4, respectively. The crystal structures of [Pd3(tmeda)3( L)2](NO3)6 ( 2), [Pd3(bpy)3( L)2](NO3)6 ( 3), and [Pd3(phen)3( L)2](NO3)6 ( 4) unequivocally support the new architecture. Two of the 'double saddle'-type complexes ( 3 and 4) are suitably crafted with π surfaces at the strategically located cis-protecting sites to facilitate intermolecular π-π interactions in the solid state. As a consequence, six units of the 3 (or 4) are assembled, by means of six-pairs of π-π stacking interactions, in a circular geometry to form an octadecanuclear molecular ring of [(Pd3L′3 L2)6] composition. The overall arrangement of the rings in the crystal packing is equated with the traditional Indian art form rangoli. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of electronic and magnetic properties of octometallic homo- and heteronuclear chromium-based molecular rings CrMF(OCH) (in short CrM, M = Cr, Cd and Ni) by the first-principle density functional theory (DFT) and pseudopotential ideas. Their radii are around 1 nm. For each CrM, the antiferromagnetic configuration corresponds to the ground state and the ferromagnetic (high spin HS) configuration to the highest energy state. Using the broken symmetry (BS) approach, the differences between the total energies of the HS configuration and all the nonequivalent low spin configurations with s = ±3/2 are calculated and exploited to extract the coupling parameters J between the magnetic ions. Magnetic moments are found to be well localised on the Cr and Ni centres, although the localisation of spin density on Ni is weaker. Having calculated the excess energies for an unprecedented number of configurations, a family of the Ising-like models with the nearest- and the next-nearest-neighbour interactions has been considered. For each CrM, the values of the interaction parameters found within the unprojected method are coherent, despite the overdetermination problem and demonstrate that the next-nearest-neighbour couplings are negligible. The DFT estimates of the nearest-neighbour coupling calculated are overestimated and the relation J/ J < 1 is not fulfilled. However, the improvement in these estimates has been achieved with respect to earlier calculations. Relying on the DFT results, the molecule is considered as a system of localised spins (or ions) S = ±3/2 and the idea to describe their interactions with itinerant electrons by the Falicov-Kimball (FK) model is suggested. In our approach, the effective magnetic interactions between ions are generated by local (on-site) Hund couplings between the ions and itinerant electrons. We demonstrate that the BS state energies obtained within DFT for CrM can be successfully represented by the FK model with a unique set of parameters. [ABSTRACT FROM AUTHOR]

Varying the polyethyleneglycol spacer between two (iso)-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some cases. These structures can be tuned by careful design of the ligand, the use of solvent and the counter ions, influencing also other important properties such as light stability and solubility. The latter is important in the context of biomedical applications, using silver compounds as antimicrobial agents. [ABSTRACT FROM AUTHOR]

Molecular Rangoli “Rangoli” is a traditional Indian art form that utilizes the concept of geometry to create beautiful patterns (see picture), as resembled by the solid ‐ state packing of the tailor ‐ made “double saddle” ‐ type trinuclear palladium(II) complexes reported by D. K. Chand et al. in their Full Paper on page 1499 ff. The palladium(II) complexes, crafted with π surfaces at strategically located positions, are found to assemble in the solid state to create octadecanuclear rings. Further interactions among the rings are considered and the term “molecular rangoli” is used to describe the packing. [ABSTRACT FROM AUTHOR]