Photochemistry seminars

Clarice D. Aiello examines evidence that quantum effects influence biological function, including magnetic sensing used in animal navigation, cellular metabolism and enzyme activity, and the capture of light energy in photosynthesis. The talk reviews proposed biophysical mechanisms and their implications for human, plant and environmental biology, while considering the difficulty of connecting observations from nanometre scales to whole organisms. A central question is whether quantum mechanics can be established or ruled out as the explanation for physiologically relevant effects, and whether those effects can be controlled for useful applications. Potential directions include biomimetic electromagnetic probes, quantum-computing architectures that operate at room temperature, improved solar-energy devices and new therapies. Progress will require work across disciplines and scales, with theory and experiment developed together.

Debashree Ghosh discusses quantum-chemistry approaches for strongly correlated polyaromatic hydrocarbons, including acenes and carotenoids. The talk examines why large valence active spaces are needed to describe optical properties and singlet–triplet gaps, and how density-matrix renormalization-group methods address these systems. Changes in molecular topology and odd-membered rings are connected to spin frustration and optical behaviour. The seminar also covers neural-network configuration interaction, connections between artificial neural networks and matrix-product-state wavefunctions, and restricted-Boltzmann-machine approaches to quantum wavefunctions. Applications include singlet fission and multiexcitonic phenomena. The hybrid event takes place in ICTP’s Euler Lecture Hall and online; the official event page provides the registration link.

Understanding photochemical mechanisms can improve both plastic recycling and protection against light-induced damage. The seminar revisits acridinium-catalysed conversion of polystyrene to benzophenone, where reactive oxygen species explain the observed chemistry rather than the previously proposed pathway. It also examines unwanted flavour changes in champagne, tracing a light-induced defect to a dimeric radical-cation intermediate. These cases connect mechanistic evidence with process optimization, industrial scale-up and possible chemical protection strategies.

Light-driven synthesis offers opportunities for more sustainable chemistry, but effective reaction design depends on understanding interactions among photons, substrates and catalysts. This seminar combines spectroscopy with kinetic analysis to resolve those mechanisms. It shows how such evidence can guide more efficient transformations and extend the range of molecules accessible through photochemical synthesis.

Photocatalyst interfaces influence both reaction efficiency and catalyst stability. This seminar examines anchoring soluble organic or organometallic catalysts onto solid supports to control those interfaces, enable greener or solvent-free conditions and simplify reuse. Combining these designs with continuous-flow processing links molecular-level improvements to scalable organic synthesis.

Triggerable materials capable of being degraded by selective stimuli stand to transform our capacity to precisely control biomedical device activity and performance while reducing the need for invasive interventions. This talk will cover the development of a modular and tunable light-triggerable hydrogel capable of interfacing with implantable devices. We have applied these materials to two applications in the gastrointestinal (GI) tract and demonstrated biocompatibility and on-demand triggering of the material in vitro, ex vivo, and in vivo. Light-triggerable hydrogels have the potential to be applied broadly throughout the GI tract and other anatomic areas. By demonstrating the first use of light-degradable hydrogels in vivo, we provide biomedical engineers and clinicians with a previously unavailable, safe, dynamically deliverable, and precise tool to design dynamically actuated implantable devices.

Nature is replete with extraordinary materials that can grow, move, respond, and adapt. In this talk I will describe our ongoing efforts to develop advanced polymeric materials, inspired by nature. First, I will describe my group’s efforts to develop ultrastiff, ultratough materials inspired by the byssal materials of marine mussels. These adhesive contacts allow mussels to secure themselves to rocks, wood, metals and other surfaces in the harsh conditions of the intertidal zone. By developing a foundational understanding of the structure-mechanics relationships and processing of the natural system, we can design high-performance materials that are extremely strong without compromising extensibility, as well as macroporous materials with tunable toughness and strength. In the second half of the talk, I will describe new efforts to exploit light as a means of remote control and power. By leveraging the phototransduction pathways of highly-absorbing, negatively photochromic molecules, we can drive the motion of amorphous polymeric materials as well as liquid flows. These innovations enable applications in packaging, connective tissue repair, soft robotics, and optofluidics.