R. Amaranatha Reddy and Carsten Tschierske discuss their hot paper on bent-core liquid crystals.

1. Can you briefly describe what you achieved in this article?
We have synthesized new bent-core liquid crystals with oligosiloxane units. Depending on the size of the siloxane units with respect to the length of the bent unit, the temperature and the substitution pattern, mesophases can be tuned from smectic (one-dimensional order) to columnar (two-dimensional structures) and cubic (three-dimensional structures). Similarly, polar order can be tuned from non-polar to ferroelectric or antiferroelectric. As shown in this paper and in earlier reports the transition from infinite layers in the smectic phases into ribbons in the columnar phases is associated with a change of the switching process from ferroelectric to antiferroelectric and from a rotation on a cone, which retains the chirality of the system to a switching around the long axis which reverses the chirality. Depending on the position and the structure of the substituent at the bent core, the intermolecular forces, as well as the bend angle can be adjusted. 

2. Could you explain the significance of your article to the non-specialist?
New bent-core liquid crystals with oligosiloxane units have been synthesized and investigated. It was demonstrated that minor modifications of the molecular structure by introduction of small substituents can completely change the properties. There is a transition between non-polar phase structures and macroscopic polar ordered mesophases. In addition, distinct types of columnar liquid crystalline phases as well as a cubic phase were obtained. Cubic phases were previously observed in lyotropic systems and for few thermoptropic liquid crystals but they were never observed in the class of bent-core mesogenic compounds.  

3. What has motivated you to conduct this work?
Bent core liquid crystals (so-called banana liquid crystals) represent ordered soft matter systems with a unique combination of properties. These molecules organize into ferroelectric as well as antiferroelectric structures and spontaneously assemble into chiral superstructures, though the molecules themselves are achiral. The structure-property relationship in bent-core compounds is still an open question, such as, the origin of ferroelectricity, the kind of molecular structures that can exhibit ferroelectric switching, the origin of achiral symmetry breaking in these systems and the understanding of the molecular organization in polar columnar phases.

4.  Where do you see this work developing in the future?
In the immediate future there will be a better understanding of the organization in the polar columnar phases as well as in the optically isotropic dark conglomerate phases, but in the medium term, we believe that there will develop different practical applications based on the polar order and chirality of these materials, such as phase modulators, fast switching electro-optical devices and NLO materials.  

5. Are there any particular challenges facing future research in this area?
Chirooptical switches based on the switching of the chirality sense by means of electric field could lead to new devices.

R. Amaranatha Reddy received his PhD in Chemistry in 2003, under Prof. B. K. Sadashiva at Raman Research Institute, India. From 2004 to 2006, he was a Humboldt Research Fellow at the Institute of Organic Chemistry, Martin-Luther-University Halle, Germany and working with Prof. Dr Carsten Tschierske. At present, he is a Research Associate in the group of Prof. David M. Walba and Prof. Noel A. Clark, at the Liquid Crystal Materials Research Centre, University of Colorado at Boulder, USA. His current research includes the synthesis of novel bent-core materials for their possible use in display devices, materials for NLO properties and surface chemistry.