Spontaneous resolution under supramolecular control

Sm and Eu(iii) lanthanide triple helicate cages based on N,N′-methylene-bis(pyridin-4-one)

Sm and Eu(iii) lanthanide triple helicate cages have two distinct metal environments, with the Sm(iii) complex exhibiting homochirality and an increase in sensitization.

Synthesis and characterization of robust three-dimensional chiral metal sulfates

Chiral three-dimensional Mg(ii) and Mn(ii) sulfates have been synthesized, well characterized and studied from first-principles calculations. High temperature X-ray diffraction, thermogravimetric analysis and DFT calculations reveal that the structures of both the compounds remain intact even after the thermal decomposition of the ammonium ion.

Syntheses, structures and photocatalytic properties of five new praseodymium–antimony oxochlorides: from discrete clusters to 3D inorganic–organic hybrid racemic compounds

Presented here are five Pr–Sb–O–Cl cluster-based compounds with structures from discrete organic-decorated cluster to 3D framework that exhibit photocatalytic H₂-evolution activity and magnetic properties.

Spontaneous chiral resolution directed by symmetry restriction and π-π interaction

In order to understand and rationally construct homochiral self-assembled structures from racemic molecules, two novel crystalline metal-organic frameworks with chiral cavities were developed. The homochirality of the layers in both MOFs was achieved by forming strong coordinate bonds between the C₃-symmetric cyclotriveratrylene and Zn₄O(CO₂)₆ cluster. By changing weak π-π interactions between organic building blocks, the achiral assembly of ZnCTV-1 was successfully transformed into a chiral assembly in ZnCTV-2. This study demonstrated a possible route for designing the synthesis of chiral MOF through weak interactions.

Development of structural complexity by liquid-crystal self-assembly

Since the discovery of the liquid-crystalline state of matter 125 years ago, this field has developed into a scientific area with many facets. This Review presents recent developments in the molecular design and self-assembly of liquid crystals. The focus is on new exciting soft-matter structures distinct from the usually observed nematic, smectic, and columnar phases. These new structures have enhanced complexity, including multicompartment and cellular structures, periodic and quasiperiodic arrays of spheres, and new emergent properties, such as ferroelctricity and spontaneous achiral symmetry-breaking. Comparisons are made with developments in related fields, such as self-assembled monolayers, multiblock copolymers, and nanoparticle arrays. Measures of structural complexity used herein are the size of the lattice, the number of distinct compartments, the dimensionality, and the logic depth of the resulting supramolecular structures.

Self-assembly structures of 1H-indazoles in the solution and solid phases: a vibrational (IR, FIR, Raman, and VCD) spectroscopy and computational study

1H-indazoles are good candidates for studying the phenomena of molecular association and spontaneous resolution of chiral compounds. Thus, because the 1H-indazoles can crystallize as dimers, trimers, or catemers, depending on their structure and the phase that they are in, the difficulty in the experimental analysis of the structure of the family of 1H-indazoles becomes clear. This difficulty leads us to contemplate several questions: How can we determine the presence of different structures of a given molecular species if they change according to the phase? Could these different structures be present in the same phase simultaneously? How can they be determined? To shed light on these questions, we outline a very complete strategy by using various vibrational spectroscopic techniques that are sensitive (VCD) and insensitive (IR, FIR, and Raman) towards the chirality, together with quantum chemical calculations.

Mirror-symmetry-breaking in poly[(9,9-di-n-octylfluorenyl- 2,7-diyl)-alt-biphenyl] (PF8P2) is susceptible to terpene chirality, achiral solvents, and mechanical stirring

Solvent chirality transfer of (S)-/(R)-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD)/circularly polarized luminescence (CPL) amplitudes with a high quantum yield of 16-20%. The present paper also reports subtle mirror-symmetry-breaking effects in CD-/CPL-amplitude and sign, CD/UV-vis spectral wavelengths, and photodynamics of the aggregates, though the reasons for the anomaly are unsolved. However, these photophysical properties depend on (i) the chemical natures of chiral and achiral molecules when used in solvent quantity, (ii) clockwise and counterclockwise stirring operations, and (iii) the order of addition of limonene and methanol to the chloroform solution.

Biomolecules at interfaces: chiral, naturally

Interfaces are a most important environment in natural and synthetic chemistries for a wide variety of processes, such as catalysis, recognition, separation, and so on. Naturally occurring systems have evolved to one handedness and the study of interfaces where biomolecules are located is a potentially revealing pursuit with regard to understanding the reasons and importance of stereochemistry in these environments. Equally, the spontaneous resolution of achiral and chiral compounds at interfaces could lead to explanations regarding the emergence of single handedness in proteins and sugars. Also, the attachment of biomolecules to surfaces leads to systems capable of stereoselective processes which may be useful for the applications mentioned above. The review covers systems ranging from small biomolecules studied under ultrapure conditions in vacuum to protein adsorption to surfaces in solution, and the techniques that can be used to study them.

Collisional activation of [14Pro+2H]2+ clusters: chiral dependence of evaporation and fission processes

Ion mobility/mass spectrometry techniques are used to investigate the dissociation of the small proline cluster [14Pro+2H](2+) produced by electrospray ionization. While this cluster is known to prefer heterochiral compositions (i.e., mixed L- and D-compositions, J. Phys. Chem. A, submitted for publication), it is possible to produce homochiral forms by electrospraying solutions containing only L- or D-proline. Differences in the measured cross sections for [14Pro+2H](2+) produced from enantiomerically pure (100% l or 100% d) or racemic (50:50 l/d) solutions indicate that homochiral and heterochiral clusters have different structures. Upon low-energy collisional activation, both the heterochiral and homochiral doubly charged structures evaporate neutral proline monomers, resulting in the formation of [xPro+2H](2+) ions (where x = 9-13). At higher activation energies, there is evidence that these smaller clusters (primarily [10Pro+2H](2+)) fission to produce [xPro+H](+) (where x = 1-6). Analysis of product ion intensities reveals a strong chiral preference associated with fissioning. Products of evaporation also show a chiral dependence but to a lesser extent.

Moiré pattern induced by the electronic coupling between 1-octanol self-assembled monolayers and graphite surface

Two-dimensional self-assembly of 1-octanol molecules on a graphite surface is investigated using scanning tunneling microscopy (STM) at the solid/liquid interface. STM images reveal that this molecule self-assembles into a compact hydrogen-bonded herringbone nanoarchitecture. Molecules are preferentially arranged in a head-to-head and tail-to-tail fashion. A Moiré pattern appears in the STM images when the 1-octanol layer is covering the graphite surface. The large Moiré stripes are perpendicular to the 1-octanol lamellae. Interpretation of the STM images suggests that the Moiré periodicity is governed by the electronic properties of the graphite surface and the 1-octanol layer periodicity.

Helicity discrimination in diaryl dichalcogenides generated by inclusion complexation with chiral hosts

Inclusion complexation of diaryl dichalcogenides with either cholic acid or chiral diols results in their helicity discrimination and an induction of optical activity that can be detected by solid-state CD measurements.

Chiroptical generation and inversion during the mirror-symmetry-breaking aggregation of dialkylpolysilanes due to limonene chirality

We observed the emergence and inversion of chiroptical handedness in three chiroptically silent dialkylpolysilanes during aggregation in limonene-methanol-THF tersolvents.