Microspheres from light—a sustainable materials platform

Driven by the demand for highly specialized polymeric materials via milder, safer, and sustainable processes, we herein introduce a powerful, purely light driven platform for microsphere synthesis – including facile synthesis by sunlight. Our light-induced step-growth precipitation polymerization produces monodisperse particles (0.4–2.4 μm) at ambient temperature without any initiator, surfactant, additive or heating, constituting an unconventional approach compared to the classically thermally driven synthesis of particles. The microspheres are formed via the Diels-Alder cycloaddition of a photoactive monomer (2-methylisophthaldialdehyde, MIA) and a suitable electron deficient dienophile (bismaleimide). The particles are stable in the dry state as well as in solution and their surface can be further functionalized to produce fluorescent particles or alter their hydrophilicity. The simplicity and versatility of our approach introduces a fresh opportunity for particle synthesis, opening access to a yet unknown material class

Ferrocene-driven single-chain polymer compaction

We introduce single-chain nanoparticles (SCNPs) exclusively folded by covalently bonded ferrocene units. Specifially, we demonstrate the ability of 2-ferrocenyl-1,10-phenanthroline to fuse single-chain collapse with the concomitant introduction of a donor functionality allowing the installation of a Pd-catalytic site, affording the first heterobimetallic ferrocene-functionalized SCNP

Tensor network simulation of polaron-polaritons in organic microcavities

In the regime of strong coupling between molecular excitons and confined optical modes, the intramolecular degrees of freedom are profoundly affected, leading to a reduced vibrational dressing of polaritons compared to bare electronically excited states. However, existing models only describe a single vibrational mode in each molecule, while actual molecules possess a large number of vibrational degrees of freedom and additionally interact with a continuous bath of phononic modes in the host medium in typical experiments. In this work, we investigate a small ensemble of molecules with an arbitrary number of vibrational degrees of freedom under strong coupling to a microcavity mode. We demonstrate that reduced vibrational dressing is still present in this case, and show that the influence of the phononic environment on most electronic and photonic observables in the lowest excited state can be predicted from just two collective parameters of the vibrational modes. Besides, we explore vibrational features that can be addressed exclusively by our extended model and could be experimentally tested. Our findings indicate that vibronic coupling is more efficiently suppressed for environments characterized by low-frequency (sub-Ohmic) modesThis work has been funded by the European Research Council (Grants No. ERC-2011-AdG-290981 and No. ERC-2016-STG-714870), and the Spanish MINECO under Contract No. MAT2014-53432-C5-5-R and the “María de Maeztu” programme for Units of Excellence in R&D (MDM- 2014-0377). F.A.Y.N.S. and A.W.C. gratefully acknowledge the support of the Winton Programme for the Physics of Sustainability and EPSR

Tensor network simulation of non-Markovian dynamics in organic polaritons

We calculate the exact many-body time dynamics of polaritonic states supported by an optical cavity filled with organic molecules. Optical, vibrational, and radiative processes are treated on an equal footing employing the time-dependent variational matrix product states algorithm. We demonstrate signatures of non-Markovian vibronic dynamics and its fingerprints in the far-field photon emission spectrum at arbitrary light-matter interaction scales, ranging from the weak to the strong coupling regimes. We analyze both the single- and many-molecule cases, showing the crucial role played by the collective motion of molecular nuclei and dark states in determining the polariton dynamics and the subsequent photon emissionThis work has been funded by the European ResearchCouncil (ERC-2011-AdG-290981 and ERC-2016-STG-714870), by the European Union Seventh FrameworkProgramme under Grant Agreement No. FP7-PEOPLE-2013-CIG-618229, and the Spanish MINECO underContract No. MAT2014-53432-C5-5-R and the“Maríade Maeztu”programme for Units of Excellence in R&D(MDM-2014-0377

Dual-Wavelength Gated oxo-Diels-Alder Photoligation

Altres ajuts: Acord transformatiu CRUE-CSICThe control of chemical functionalization with orthogonal light stimuli paves the way toward manipulating materials with unprecedented spatiotemporal resolution. To reach this goal, we herein introduce a photochemical reaction system that enables two-color control of covalent ligation via an oxo-Diels-Alder cycloaddition between two separate light-responsive molecular entities: a UV-activated photocaged diene based on ortho-quinodimethanes and a carbonyl dienophile appended to a diarylethene photoswitch, whose reactivity can be modulated upon illumination with UV and visible light

Visible‐Light‐Induced Control over Reversible Single‐Chain Nanoparticle Folding

We introduce a class of single-chain nanoparticles (SCNPs) that respond to visible light (λ$_{max}$=415 nm) with complete unfolding from their compact structure into linear chain analogues. The initial folding is achieved by a simple esterification reaction of the polymer backbone constituted of acrylic acid and polyethylene glycol carrying monomer units, introducing bimane moieties, which allow for the photochemical unfolding, reversing the ester-bond formation. The compaction and the light driven unfolding proceed cleanly and are readily followed by size exclusion chromatography (SEC) and diffusion ordered NMR spectroscopy (DOSY), monitoring the change in the hydrodynamic radius (R$_H$). Importantly, the folding reaction and the light-induced unfolding are reversible, supported by the high conversion of the photo cleavage. As the unfolding reaction occurs in aqueous systems, the system holds promise for controlling the unfolding of SCNPs in biological environments

Fano resonances and decoherence in transport through quantum dots

A tunable microwave scattering device is presented which allows the controlled variation of Fano line shape parameters in transmission through quantum billiards. We observe a non-monotonic evolution of resonance parameters that is explained in terms of interacting resonances. The dissipation of radiation in the cavity walls leads to decoherence and thus to a modification of the Fano profile. We show that the imaginary part of the complex Fano q-parameter allows to determine the absorption constant of the cavity. Our theoretical results demonstrate further that the two decohering mechanisms, dephasing and dissipation, are equivalent in terms of their effect on the evolution of Fano resonance lineshapes.Comment: 9 pages, 7 figures, submitted to Physica E (conference proceedings

Wavelength-Gated Photochemical Synthesis of Phenalene Diimides

Herein, we pioneer a wavelength‐gated synthesis route to phenalene diimides. Consecutive Diels–Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro‐phenalene‐1,6‐diol diimides via 5‐formyl‐hexahydro‐benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82–99 % yield) and exhibit excellent diastereoselectivity (62–98 % d.r.). The wavelength‐gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin‐active molecules