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ortho-Substituted 2-Phenyldihydroazulene Photoswitches: Enhancing the Lifetime of the Photoisomer by ortho-Aryl Interactions. Molecules 2021; 26:molecules26216462. [PMID: 34770871 PMCID: PMC8588411 DOI: 10.3390/molecules26216462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/19/2021] [Accepted: 10/23/2021] [Indexed: 11/17/2022] Open
Abstract
Photochromic molecules are systems that undergo a photoisomerization to high-energy isomers and are attractive for the storage of solar energy in a closed-energy cycle, for example, in molecular solar thermal energy storage systems. One challenge is to control the discharge time of the high-energy isomer. Here, we show that different substituents in the ortho position of a phenyl ring at C-2 of dihydroazulene (DHA-Ph) significantly increase the half-life of the metastable vinylheptafulvene (VHF-Ph) photoisomer; thus, the energy-releasing VHF-to-DHA back-reaction rises from minutes to days in comparison to the corresponding para- and meta-substituted systems. Systems with two photochromic DHA-Ph units connected by a diacetylene bridge either at the para, meta and ortho positions and corresponding to a linear or to a cross-conjugated pathway between the two photochromes are also presented. Here, the ortho substitution was found to compromise the switching properties. Thus, irradiation of ortho-bridged DHA-DHA resulted in degradation, probably due to the proximity of the different functional groups that can give rise to side-reactions.
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Pirone D, Bandeira NAG, Tylkowski B, Boswell E, Labeque R, Garcia Valls R, Giamberini M. Contrasting Photo-Switching Rates in Azobenzene Derivatives: How the Nature of the Substituent Plays a Role. Polymers (Basel) 2020; 12:E1019. [PMID: 32365778 PMCID: PMC7284787 DOI: 10.3390/polym12051019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/20/2020] [Accepted: 04/26/2020] [Indexed: 11/20/2022] Open
Abstract
A molecular design approach was used to create asymmetrical visible light-triggered azo-derivatives that can be good candidates for polymer functionalization. The specific electron-donor substituted molecules were characterized and studied by means of NMR analyses and UV-visible spectroscopy, comparing the results with Time Dependent Density Functional (TD-DFT) calculations. A slow rate of isomerization (ki = 1.5 × 10-4 s-1) was discovered for 4-((2-hydroxy-5methylphenyl) diazenyl)-3-methoxybenzoic acid (AZO1). By methylating this moiety, it was possible to unlock the isomerization mechanism for the second molecule, methyl 3-methoxy-4-((2-methoxy-5-methylphenyl) diazenyl)benzoate (AZO2), reaching promising isomerization rates with visible light irradiation in different solvents. It was discovered that this rate was heightened by one order of magnitude (ki = 3.1 × 10-3 s-1) for AZO2. A computational analysis using density functional (DFT/PBE0) and wavefunction (QD-NEVPT2) methodologies provided insight into the photodynamics of these systems. Both molecules require excitation to the second (S2) excited state situated in the visible region to initiate the isomerization. Two classic mechanisms were considered, namely rotation and inversion, with the former being energetically more favorable. These azo-derivatives show potential that paves the way for future applications as building blocks of functional polymers. Likewise, they could be really effective for the modification of existing commercial polymers, thus transferring their stimuli responsive properties to polymeric bulky structures, converting them into smart materials.
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Affiliation(s)
- Domenico Pirone
- Department of Chemical Engineering (DEQ), Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain; (D.P.); (R.G.V.)
- Procter & Gamble Services Company n.v., Temselaan 100, 1853 Strombeek-Bever, Belgium;
| | - Nuno A. G. Bandeira
- BioISI—Biosystems & Integrative Sciences Institute; C8, Faculdade de Ciências, Universidade de Lisboa Campo Grande, 1749-016 Lisboa, Portugal;
| | - Bartosz Tylkowski
- Eurecat, Centre Tecnològic de Catalunya, C/Marcel-lí Domingo, 43007 Tarragona, Spain;
| | - Emily Boswell
- The Procter and Gamble Company, 8611 Beckett Rd, West Chester Township, Cincinnati, OH 45069, USA;
| | - Regine Labeque
- Procter & Gamble Services Company n.v., Temselaan 100, 1853 Strombeek-Bever, Belgium;
| | - Ricard Garcia Valls
- Department of Chemical Engineering (DEQ), Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain; (D.P.); (R.G.V.)
- Eurecat, Centre Tecnològic de Catalunya, C/Marcel-lí Domingo, 43007 Tarragona, Spain;
| | - Marta Giamberini
- Department of Chemical Engineering (DEQ), Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain; (D.P.); (R.G.V.)
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Pirone D, Marturano V, Del Pezzo R, Fernández Prieto S, Underiner T, Giamberini M, Tylkowski B. Molecular Design of Microcapsule Shells for Visible Light-Triggered Release. Polymers (Basel) 2019; 11:E904. [PMID: 31108926 PMCID: PMC6572248 DOI: 10.3390/polym11050904] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/13/2019] [Accepted: 05/14/2019] [Indexed: 12/19/2022] Open
Abstract
The development of photo-responsive capsules to tune and control the sustained-release of encapsulated actives is a fascinating and challenging route to improve the performances and effectiveness of a wide range of delivery applications. In this work, we report the preparation of visible light-responsive capsules obtained via oil-in-water interfacial polycondensation between modified diacyl-chloride azobenzene moiety and diamine flexible spacer in the presence of cross-linkers with different structures and functionalities. The effect on the release profile of the encapsulated perfume oil was investigated using three flexible spacers with different lengths (1,8-diaminooctane; 1,6-diaminohexane and 1,4-diaminobutane) and two types of cross-linkers (1,3,5-benzenetricarbonyl trichloride and melamine). We analyzed how the properties of microcapsules can be tailored changing the design of the shell structure. Fine tuning of the perfume release profiles was obtained. The changes in capsules size and morphology due to visible light irradiation were monitored via light scattering, optical microscopy and atomic force microscopy. Perfume release was 50% faster in the systems prepared with melamine as the cross-linker. Modelling studies were carried out to support the discussion of the experimental results.
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Affiliation(s)
- Domenico Pirone
- Department of Chemical Engineering, Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain.
- Centre Tecnològic de la Química de Catalunya, Carrer Marcelli Domingo s/n, 43007 Tarragona, Spain.
- Procter & Gamble Services Company n.v., Temselaan 100, 1853 Strombeek-Bever, Belgium.
| | - Valentina Marturano
- Department of Chemical, Materials, and Production Engineering (DICMAPI), University of Naples "Federico II", P. le Tecchio, 80, 80125 Napoli, Italy.
| | - Rita Del Pezzo
- Department of Chemical Engineering, Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain.
- Centre Tecnològic de la Química de Catalunya, Carrer Marcelli Domingo s/n, 43007 Tarragona, Spain.
- Procter & Gamble Services Company n.v., Temselaan 100, 1853 Strombeek-Bever, Belgium.
| | | | - Todd Underiner
- The Procter and Gamble Company, 6210 Center Hill Avenue, Cincinnati, OH 45224, USA.
| | - Marta Giamberini
- Department of Chemical Engineering, Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain.
| | - Bartosz Tylkowski
- Department of Chemical Engineering, Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain.
- Centre Tecnològic de la Química de Catalunya, Carrer Marcelli Domingo s/n, 43007 Tarragona, Spain.
- The Procter and Gamble Company, 6210 Center Hill Avenue, Cincinnati, OH 45224, USA.
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