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Clark JA, Robinson S, Espinoza EM, Bao D, Derr JB, Croft L, O'Mari O, Grover WH, Vullev VI. Poly(dimethylsiloxane) as a room-temperature solid solvent for photophysics and photochemistry. Phys Chem Chem Phys 2024; 26:8062-8076. [PMID: 38372740 DOI: 10.1039/d3cp05413f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Medium viscosity strongly affects the dynamics of solvated species and can drastically alter the deactivation pathways of their excited states. This study demonstrates the utility of poly(dimethylsiloxane) (PDMS) as a room-temperature solid-state medium for optical spectroscopy. As a thermoset elastic polymer, PDMS is transparent in the near ultraviolet, visible, and near infrared spectral regions. It is easy to mould into any shape, forming surfaces with a pronounced smoothness. While PDMS is broadly used for the fabrication of microfluidic devices, it swells in organic solvents, presenting severe limitations for the utility of such devices for applications employing non-aqueous fluids. Nevertheless, this swelling is reversible, which proves immensely beneficial for loading samples into the PDMS solid matrix. Transferring molecular-rotor dyes (used for staining prokaryotic cells and amyloid proteins) from non-viscous solvents into PDMS induces orders-of-magnitude enhancement of their fluorescence quantum yield and excited-state lifetimes, providing mechanistic insights about their deactivation pathways. These findings demonstrate the unexplored potential of PDMS as a solid solvent for optical applications.
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Affiliation(s)
- John A Clark
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Samantha Robinson
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Eli M Espinoza
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Duoduo Bao
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - James B Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Luca Croft
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Omar O'Mari
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - William H Grover
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Valentine I Vullev
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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Yang MY, O’Mari O, Goddard WA, Vullev VI. How Permanent Are the Permanent Macrodipoles of Anthranilamide Bioinspired Molecular Electrets? J Am Chem Soc 2024; 146:5162-5172. [PMID: 38226894 PMCID: PMC10916682 DOI: 10.1021/jacs.3c10525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 01/17/2024]
Abstract
Dipoles are ubiquitous, and their impacts on materials and interfaces affect many aspects of daily life. Despite their importance, dipoles remain underutilized, often because of insufficient knowledge about the structures producing them. As electrostatic analogues of magnets, electrets possess ordered electric dipoles. Here, we characterize the structural dynamics of bioinspired electret oligomers based on anthranilamide motifs. We report dynamics simulations, employing a force field that allows dynamic polarization, in a variety of solvents. The results show a linear increase in macrodipoles with oligomer length that strongly depends on solvent polarity and hydrogen-bonding (HB) propensity, as well as on the anthranilamide side chains. An increase in solvent polarity increases the dipole moments of the electret structures while decreasing the dipole effects on the moieties outside the solvation cavities. The former is due to enhancement of the Onsager reaction field and the latter to screening of the dipole-generated fields. Solvent dynamics hugely contributes to the fluctuations and magnitude of the electret dipoles. HB with the solvent weakens electret macrodipoles without breaking the intramolecular HB that maintains their extended conformation. This study provides design principles for developing a new class of organic materials with controllable electronic properties. An animated version of the TOC graphic showing a sequence of the MD trajectories of short and long molecular electrets in three solvents with different polarities is available in the HTML version of this paper.
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Affiliation(s)
- Moon Young Yang
- Materials
and Process Simulation Center, California
Institute of Technology, Pasadena, California 91125, United States
| | - Omar O’Mari
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
| | - William A. Goddard
- Materials
and Process Simulation Center, California
Institute of Technology, Pasadena, California 91125, United States
| | - Valentine I. Vullev
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
- Department
of Chemistry, University of California, Riverside, California 92521, United States
- Department
of Biochemistry, University of California, Riverside, California 92521, United States
- Materials
Science and Engineering Program, University
of California, Riverside, California 92521, United States
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O’Mari O, Vullev VI. Optical Window to Polarity of Electrolyte Solutions. Molecules 2023; 28:4360. [PMID: 37298836 PMCID: PMC10254283 DOI: 10.3390/molecules28114360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/21/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
Medium polarity plays a crucial role in charge-transfer processes and electrochemistry. The added supporting electrolyte in electrochemical setups, essential for attaining the needed electrical conductivity, sets challenges for estimating medium polarity. Herein, we resort to Lippert-Mataga-Ooshika (LMO) formalism for estimating the Onsager polarity of electrolyte organic solutions pertinent to electrochemical analysis. An amine derivative of 1,8-naphthalimide proves to be an appropriate photoprobe for LMO analysis. An increase in electrolyte concentration enhances the polarity of the solutions. This effect becomes especially pronounced for low-polarity solvents. Adding 100 mM tetrabutylammonium hexafluorophosphate to chloroform results in solution polarity exceeding that of neat dichloromethane and 1,2-dichloroethane. Conversely, the observed polarity enhancement that emerges upon the same electrolyte addition to solvents such as acetonitrile and N,N-dimethylformamide is hardly as dramatic. Measured refractive indices provide a means for converting Onsager to Born polarity, which is essential for analyzing medium effects on electrochemical trends. This study demonstrates a robust optical means, encompassing steady-state spectroscopy and refractometry, for characterizing solution properties important for charge-transfer science and electrochemistry.
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Affiliation(s)
- Omar O’Mari
- Department of Bioengineering, University of California, Riverside, CA 92521, USA;
| | - Valentine I. Vullev
- Department of Bioengineering, University of California, Riverside, CA 92521, USA;
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Material Science and Engineering Program, University of California, Riverside, CA 92521, USA
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