Physical Chemistry seminars

Richard Robson, Susumu Kitagawa and Omar M. Yaghi examine the origins, development and applications of metal–organic frameworks. Robson follows the emergence of coordination polymers and the design of extended molecular structures from pre-organized building blocks, explaining the architectural ideas behind framework construction. Kitagawa describes how coordination chemistry led to porous materials and then to flexible crystalline structures. His discussion of soft porous crystals shows how frameworks can respond to external stimuli, opening and closing as they capture molecules, with implications for gas storage and separation. Yaghi considers how fundamental framework chemistry can connect to industrial and societal applications, including emerging uses of artificial intelligence. Together, the lectures show how complementary approaches to molecular design, porosity and responsive structure developed into a broad materials research field.

Sijbren Otto explores how features associated with life can arise from initially lifeless chemical components. The systems couple reversible oligomerization of comparatively simple molecular building blocks with self-assembly. Their behavior includes the spontaneous appearance of self-replicating molecules, catalytic activity extending beyond autocatalysis, and the breaking of chiral symmetry. These observations connect the emergence of molecular replication and catalysis with the origins of biological handedness.

Living systems select one molecular handedness, making the origin of homochirality a central problem in understanding how life began. David Lacoste examines how this asymmetry can emerge in autocatalytic chemical networks when they contain sufficiently many chiral species and operate far from equilibrium. Polymerization greatly expands molecular diversity, raising the question of whether it can also generate and preserve a preference for one handedness. The talk develops this connection through an RNA reactor model, studying the conditions under which template-directed ligation and polymerization produce and maintain homochirality.

Aleksey Yekimov, Louis Brus and Moungi Bawendi trace the discovery and chemical development of quantum dots: semiconductor particles whose electronic and optical behaviour changes with their size. Yekimov examines confinement effects in small crystals embedded in glass, while Brus develops the study of semiconductor particles dispersed in solution. Bawendi explains the synthetic challenge of producing high-quality nanocrystals with controlled dimensions and how more reliable preparation made their properties experimentally and practically useful. The lectures bring together the physics of confinement, the chemistry of colloidal materials and the control of particle growth, showing why both discovery and synthesis were essential to the emergence of quantum-dot science.

Donna Blackmond examines two linked problems in the origin of life: how an initially balanced mixture of molecular mirror images could acquire a handedness bias, and how that small bias could be amplified. She compares four experimental approaches using chemical kinetics and solid–solution equilibria. The first is asymmetric autocatalysis, including the Soai reaction and kinetic models connecting self-replication with suppression of the opposite enantiomer. Blackmond distinguishes this powerful model from a demonstrated prebiotic pathway. She then discusses amplification through eutectic partitioning and through attrition-enhanced deracemization, where dissolution, crystal growth and interconversion can produce a single-handed solid. The final approach incorporates stereochemical selection into plausible prebiotic chemistry. Examples explore reciprocal enrichment involving sugars and amino-acid precursors. The lecture argues that accounts of how biological building blocks arose must explain their chirality alongside their synthesis.

The richness of active matter's spatiotemporal patterns continues to capture our imagination. Shaping these emergent dynamics into pre-determined forms of our choosing is a grand challenge in the field. To complicate matters, multiple dynamical attractors can coexist in such systems, leading to initial condition-dependent dynamics. Consequently, non-trivial spatiotemporal inputs are generally needed to access these states. Optimal control theory provides a general framework for identifying such inputs and represents a promising computational tool for guiding experiments and interacting with various systems in soft active matter and biology. As an exemplar, I first consider an extensile active nematic fluid confined to a disk. In the absence of control, the system produces two topological defects that perpetually circulate. Optimal control identifies a time-varying active stress field that restructures the director field, flipping the system to its other attractor that rotates in the opposite direction. As a second, analogous case, I examine a small network of coupled Belousov-Zhabotinsky chemical oscillators that possesses two dominant attractors, two wave states of opposing chirality. Optimal control similarly achieves the task of attractor switching. I conclude with a few forward-looking remarks on how the same model-based control approach might come to bear on problems in biology.