60 research outputs found
Microspheres from lightâa 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 â including facile synthesis by sunlight. Our light-induced step-growth precipitation polymerization produces monodisperse particles (0.4â2.4 ÎŒm) 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 âMarĂa de
Maeztuâ 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
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
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 theâMarĂade Maeztuâprogramme for Units of Excellence in R&D(MDM-2014-0377
VisibleâLightâInduced Control over Reversible SingleâChain Nanoparticle Folding
We introduce a class of single-chain nanoparticles (SCNPs) that respond to visible light (λ=415â
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). 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 wavelengthâgated synthesis route to phenalene diimides. Consecutive DielsâAlder reactions of methylisophthalaldehydes and maleimides afford hexahydroâphenaleneâ1,6âdiol diimides via 5âformylâhexahydroâbenzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82â99â% yield) and exhibit excellent diastereoselectivity (62â98â%â
d.r.). The wavelengthâgated 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 spinâactive molecules
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