Molecular shape is an important factor in determining the material properties of thermotropic liquid crystals (LCs). We synthesized and investigated several LC compounds formed by asymmetrically bent molecules with a rigid four-ring core in the shape of the letter 'L'. We measured the temperature dependencies of dielectric permittivities, birefringence, splay K 1 and bend K 3 elastic constants, splay viscosity h splay and flow viscosities h || and h t . The bend-splay anisotropy dK 31 ¼ K 3 À K 1 is negative, similar to the case of nematic LCs formed by symmetrically bent molecules of V-shape. The dielectric anisotropy D3 and birefringence are positive in the entire nematic range. The splay viscosity h splay and the flow viscosities h || and h t are smaller than the viscosities measured for the symmetric V-shaped bent-core materials at similar temperatures. The ratio G ¼ h splay /h ||,t is in the range 5-4 that is typical for rod-like LCs. The reported L-shaped bent-core nematic LCs combine the useful features of bent-core LCs (such as a negative dK 31 , suitable for formulation of broad-range blue phases) with the relatively low viscosities, a property typical for rod-like LCs and beneficial for electro-optic switching applications.

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The ambiphilic Ge(II) and Sn(II) cationic species have been reported to be isolated through kinetic or thermodynamic stabilizations. Nonetheless, steric congestion or excessive coordination of donor atoms to the cationic center concurrently disfavors its prompt reactivity. Our research in this field revolves around the utilization of structurally non-rigid bis(imine) based tetradentate supporting ligands for the stabilization of Ge(II) and Sn(II) cationic species. Such E(II) cationic systems have been advantaged due to inherent flexibility present at the ligand backbone allowing disposal of E(II) orbitals through geometric rearrangements for further reactivity. The bifunctionality present in the ligand enables the first examples of Ge(II) bismonocations. Furthermore, the redox-active nature of the ligand encourages participation in chemical transformations. In this personal account we have provided a detailed discussion of our published work in this direction in the last five years.

The intramolecularly double‐donor‐stabilized stannylene 1 has been synthesized from the salt‐metathesis reaction between two equivalents of lithium pyridine ene‐amide L1 and SnCl2. Compound 1 exhibits dipolar behavior when reacted with B(C6F5)3 leading to the zwitterionic compound 2. The reaction of 1 with one equivalent and 0.5 equivalent of AgOTf (OTf=trifluoromethane sulfonate) result in the formation of a stannylene‐AgOTf complex 3 and a homoleptic distannylene‐silver ionic complex 4, respectively. Analogous to complex 4, the gold(I) complex 5 has been synthesized from the reaction between two equivalents of 1 and 0.5 equivalent of AuCl.SMe2/Me3SiOTf. Complex 5 is the first example of homoleptic stannylene‐Au(I) ionic complex among the very scarce reports on stannylene‐gold(I) coordination complexes. All compounds have been structurally characterized using single crystal X‐ray crystallography. Solution‐state characterization have been performed using multinuclear NMR techniques. Detailed DFT calculations on the optimized geometries 1 o, 3 o–5 o reveal the change in sp‐ hybridization on the pyramidal Sn(II) center upon metal coordination and their bonding overlaps.

The synthesis and characterization of stable achiral unsymmetrical four-ring banana-shaped molecules consisting of a laterally chloro substituted 3,4 0 -disubstituted biphenyl unit with an ester linkage between the phenyl rings as the central unit in 4-(N-4 0 -n-tetradecyloxysalicylidene)aminophenyl [2chloro-5-(N-4 0 -n-tetradecyloxysalicylidene) aminobenzoate] and 4-(N-4 0 -n-alkyloxysalicylidene) aminophenyl [4-chloro-5-(N-4 0 -n-alkyloxysalicylidene) aminobenzoate] are presented. These compounds are thermally and hydrolytically stable due to intramolecular hydrogen bonding and exhibit polarization splay modulated and layer undulated (PMLU) B7/B1 Rev/Tilted (2D-polarization modulated layer undulated smectic phase, B1 RevTilt phase) phase variants. The phase transitions have been confirmed by differential scanning calorimetry and the phases are characterized by polarized optical microscopy. Two representative examples have been characterized by X-ray diffraction studies. DFT calculations of the bending angle, dipole moments, molecular polarizabilities and voltage holding ratio are also presented.