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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Benchmarking Guanidinium Organosulfonate Hydrogen-Bonded Frameworks for Structure Determination of Encapsulated Guests

Single crystal X-ray diffraction (SCXRD) is arguably the most definitive method for molecular structure determination, but it is often challenged by compounds that are liquids or oils at room temperature or do not form crystals adequate for analysis. Our laboratory previously reported a simple, cost-effective, single-step crystallization method based on guanidinium organosulfonate (GS) hydrogen bonded frameworks for structure determination of a wide range of encapsulated guest molecules, including assignment of the absolute configuration of chiral centers. Herein, we expand on those results and report a head-to-head comparison of the GS method with adamantoid “molecular chaperones”, which have been reported to be useful hosts for structure determination. Inclusion compounds limited to only two GS hosts are characterized by low R1 values and Flack parameters, infrequent disorder of the host and guest, and manageable disorder when it does exist. The structures of some target molecules that were not included or resolved using the adamantoid chaperones were successfully included and resolved by the GS hosts, and vice versa. Of the 32 guests attempted by the GS method, 31 inclusion compounds afforded successful guest structure solutions, a 97% success rate. The GS hosts and adamantoid chaperones are complementary with respect to guest inclusion, arguing that both should be employed in the arsenal of methods for structure determination. Furthermore, the low cost of organosulfonate host components promises an accessible route to molecular structure determination for a wide range of users.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Challenging excited states from adaptive quantum eigensolvers: subspace expansions vs. state-averaged strategies

The prediction of electronic structure for strongly correlated molecules represents a promising application for near-term quantum computers. Significant attention has been paid to ground state wavefunctions, but excited states of molecules are relatively unexplored. In this work, we consider the adaptive, problem-tailored (ADAPT)-variational quantum eigensolver (VQE) algorithm, a single-reference approach for obtaining ground states, and its state-averaged generalization for computing multiple states at once. We demonstrate for both rectangular and linear H4, as well as for BeH2, that this approach, which we call multistate-objective, Ritz-eigenspectral (MORE)-ADAPT-VQE, can make better use of small excitation manifolds than an analogous method based on a single-reference ADAPT-VQE calculation, q-sc-EOM. In particular, MORE-ADAPT-VQE is able to accurately describe both avoided crossings and crossings between states of different symmetries. In addition to more accurate excited state energies, MORE-ADAPT-VQE can recover accurate transition dipole moments in situations where traditional ADAPT-VQE and q-sc-EOM struggle. These improvements suggest a promising direction toward the use of quantum computers for difficult excited state problems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on H7CSeN3O4 by Materials Project

NH3CH2(NO)2H2SeO2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules; four H2SeO2 clusters; and four ~{n},~{n}'-dihydroxymethanimidamide molecules. In each H2SeO2 cluster, there are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. Se2- is bonded in a distorted L-shaped geometry to two O2- atoms. Both Se–O bond lengths are 1.85 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one Se2- atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one Se2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HC2 by Materials Project

C2H crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two coronene molecules. there are twelve inequivalent C+0.50- sites. In the first C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–C bond length is 1.42 Å. The C–H bond length is 1.09 Å. In the second C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. All C–C bond lengths are 1.43 Å. In the third C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. The C–C bond length is 1.42 Å. In the fourth C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. Both C–C bond lengths are 1.43 Å. In the fifth C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–H bond length is 1.09 Å. In the sixth C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–C bond length is 1.42 Å. The C–H bond length is 1.09 Å. In the seventh C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. The C–C bond length is 1.43 Å. In the eighth C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. The C–C bond length is 1.42 Å. In the ninth C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–H bond length is 1.09 Å. In the tenth C+0.50- site, C+0.50- is bonded in a trigonal planar geometry to three C+0.50- atoms. Both C–C bond lengths are 1.43 Å. In the eleventh C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–H bond length is 1.09 Å. In the twelfth C+0.50- site, C+0.50- is bonded in a distorted single-bond geometry to one C+0.50- and one H1+ atom. The C–H bond length is 1.09 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H2C3 by Materials Project

C3H2 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four 2,3-dimethyl-1,3-butadiene molecules. there are three inequivalent C+0.67- sites. In the first C+0.67- site, C+0.67- is bonded in a distorted single-bond geometry to one C+0.67- and one H1+ atom. The C–C bond length is 1.41 Å. The C–H bond length is 1.09 Å. In the second C+0.67- site, C+0.67- is bonded in a distorted single-bond geometry to one C+0.67- and one H1+ atom. The C–C bond length is 1.41 Å. The C–H bond length is 1.09 Å. In the third C+0.67- site, C+0.67- is bonded in a trigonal planar geometry to three C+0.67- atoms. The C–C bond length is 1.48 Å. H1+ is bonded in a single-bond geometry to one C+0.67- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgS8N9(ClO6)2 by Materials Project

(NAgN)2N2(NS2)4(N2Cl)4(SO3)8 crystallizes in the tetragonal I-42d space group. The structure is zero-dimensional and consists of four ammonia molecules, sixteen sulfur trioxide molecules, eight N2Cl clusters, four NAgN clusters, and eight NS2 clusters. In each N2Cl cluster, N+4.56+ is bonded in a single-bond geometry to one Cl1- atom. The N–Cl bond length is 1.50 Å. Cl1- is bonded in a distorted bent 150 degrees geometry to two equivalent N+4.56+ atoms. In each NAgN cluster, Ag1+ is bonded in a distorted linear geometry to two equivalent N+4.56+ atoms. Both Ag–N bond lengths are 2.07 Å. N+4.56+ is bonded in a single-bond geometry to one Ag1+ atom. In each NS2 cluster, N+4.56+ is bonded in a linear geometry to two equivalent S2- atoms. Both N–S bond lengths are 1.53 Å. S2- is bonded in a distorted single-bond geometry to one N+4.56+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Collisional excitation of interstellar PN by H 2 : New interaction potential and scattering calculations

Here, rotational excitation of interstellar PN molecules induced by collisions with H 2 is investigated. We present the first ab initio four-dimensional potential energy surface (PES) for the PN–H 2 van der Waals system. The PES was obtained using an explicitly correlated coupled cluster approach with single, double, and perturbative triple excitations [CCSD(T)-F12b]. The method of interpolating moving least squares was used to construct an analytical PES from these data. The equilibrium structure of the complex was found to be linear, with H 2 aligned at the N end of the PN molecule, at an intermolecular separation of 4.2 Å. The corresponding well-depth is 224.3 cm -1 . The dissociation energies were found to be 40.19 cm -1 and 75.05 cm -1 for complexes of PN with ortho-H 2 and para-H 2 , respectively. Integral cross sections for rotational excitation in PN–H 2 collisions were calculated using the new PES and were found to be strongly dependent on the rotational level of the H 2 molecule. These new collisional data will be crucial to improve the estimation of PN abundance in the interstellar medium from observational spectra.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Dissecting the structural heterogeneity of proteins by native mass spectrometry

Abstract A single gene yields many forms of proteins via combinations of posttranscriptional/posttranslational modifications. Proteins also fold into higher‐order structures and interact with other molecules. The combined molecular diversity leads to the heterogeneity of proteins that manifests as distinct phenotypes. Structural biology has generated vast amounts of data, effectively enabling accurate structural prediction by computational methods. However, structures are often obtained heterologously under homogeneous states in vitro. The lack of native heterogeneity under cellular context creates challenges in precisely connecting the structural data to phenotypes. Mass spectrometry (MS) based proteomics methods can profile proteome composition of complex biological samples. Most MS methods follow the “bottom‐up” approach, which denatures and digests proteins into short peptide fragments for ease of detection. Coupled with chemical biology approaches, higher‐order structures can be probed via incorporation of covalent labels on native proteins that are maintained at the peptide level. Alternatively, native MS follows the “top‐down” approach and directly analyzes intact proteins under nondenaturing conditions. Various tandem MS activation methods can dissect the intact proteins for in‐depth structural elucidation. Herein, we review recent native MS applications for characterizing heterogeneous samples, including proteins binding to mixtures of ligands, homo/hetero‐complexes with varying stoichiometry, intrinsically disordered proteins with dynamic conformations, glycoprotein complexes with mixed modification states, and active membrane protein complexes in near‐native membrane environments. We summarize the benefits, challenges, and ongoing developments in native MS, with the hope to demonstrate an emerging technology that complements other tools by filling the knowledge gaps in understanding the molecular heterogeneity of proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Study of Self-Interaction Errors in Density Functional Calculations of Magnetic Exchange Coupling Constants Using Three Self-Interaction Correction Methods

We examine the role of self-interaction errors (SIE) removal on the evaluation of magnetic exchange coupling constants. In particular we analyze the effect of scaling down the self-interaction-correction (SIC) for three non-empirical density functional approximations (DFAs) namely, the local spin density approximation, the Perdew-Burke-Ernzerhof generalized gradient approximation, and recent SCAN family of meta-GGA functionals. To this end, we employ three one-electron SIC methods: Perdew-Zunger [Perdew, J. P.; Zunger, A. Phys. Rev. B, 1981, 23, 5048] SIC, the orbitalwise scaled SIC method [Vydrov, O. A. et al., J. Chem. Phys. 2006, 124, 094108], and the recent local scaling method [Zope, R. R. et al., J. Chem. Phys. 2019, 151, 214108]. We compute the magnetic exchange coupling constants using the spin projection and non projection approaches for sets of molecules composed of dinuclear and polynuclear H-He models, organic radical molecules, and chlorocuprate, and compare these results against accurate theories and experiment. Our results show that for the systems that mainly consist of single electron regions, PZSIC performs well but for more complex organic systems and the chlorcuprates, an overcorrecting tendency of PZSIC combined with the DFAs utilized in this work is more pronounced, and in such cases LSIC with kinetic energy density ratio performs better than PZSIC. Furthermore, analysis of the results in terms of SIC corrections to the density and to the total energy shows that both density and energy correction are required to obtain an improved prediction of magnetic exchange couplings.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Spectra-Orthogonal Optical Anisotropy in Wafer-Scale Molecular Crystal Monolayers

Controlling the spectral and polarization response of two-dimensional (2D) crystals is vital for developing ultrathin platforms for compact optoelectronic devices. However, independently tuning optical anisotropy and spectral response remains challenging in conventional semiconductors due to the intertwined nature of their lattice and electronic structures. Here, we report spectra-orthogonal optical anisotropy─where polarization anisotropy is tuned independently of spectral response─in wafer-scale, one-atom-thick 2D molecular crystal (2DMC) monolayers synthesized on monolayer transition-metal dichalcogenide (TMD) crystals. Utilizing the concomitant spectral consistency and structural tunability of perylene derivatives, we demonstrate tunable optical polarization anisotropy in 2DMCs with similar spectral profiles, as confirmed by room-temperature scanning tunneling microscopy and cross-polarized reflectance microscopy. Additional angle-dependent analysis of the single-crystal and polycrystalline molecular domains reveals an epitaxial relationship between the 2DMC and TMD. In conclusion, our results establish a scalable, molecule-based 2D crystalline platform for unique and tunable functionalities unattainable in covalent 2D solids.

2D materials↗
DOE OSTI2023

Double-Atom Catalysts Featuring Inverse Sandwich Structure for CO 2 Reduction Reaction: A Synergetic First-Principles and Machine Learning Investigation

Electrocatalytic CO 2 reduction reactions (CO 2 RR) based on scalable and highly efficient catalysis provide an attractive strategy for reducing CO 2 emissions. Here in this work, we combined first-principles density functional theory (DFT) and machine learning (ML) to comprehensively explore the potential of double-atom catalysts (DACs) featuring an inverse sandwich structure anchored on defective graphene (gra) to catalyze CO 2 RR to generate C 1 products. We started with five homonuclear M 2 ⊥gra (M = Co, Ni, Rh, Ir, and Pt), followed by 127 heteronuclear MM'⊥gra (M = Co, Ni, Rh, Ir, and Pt, M' = Sc–Au). Stable DACs were screened by evaluating their binding energy, formation energy, and dissolution potential of metal atoms, as well as conducting first-principles molecular dynamics simulations with and without solvent water molecules. Based on DFT calculations, Rh 2 ⊥gra DAC was found to outperform the other four homonuclear DACs and the Rh-based single- and double-atom catalysts of noninverse sandwich structures. Out of the 127 heteronuclear DACs, 14 were found to be stable and have good catalytic performance. An ML approach was adopted to correlate key factors with the activity and stability of the DACs, including the sum of radii of metal and ligand atoms (d M–M' , d M–C , and d M'–C ), the sum and difference of electronegativity of two metal atoms (P M + P M' , P M – P M '), the sum and difference of first ionization energy of two metal atoms (I M + I M' , I M – I M '), the sum and difference of electron affinity of two metal atoms (A M + A M' , A M – A M '), and the number of d-electrons of the two metal atoms (Nd). The obtained ML models were further used to predict 154 potential electrocatalysts out of 784 possible DACs featuring the same inverse sandwich configuration. Overall, this work not only identified promising CO 2 RR DACs featuring the reported inverse sandwich structure but also provided insights into key atomic characteristics associated with high CO 2 RR activity.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Mixed Plastics Waste Valorization through Tandem Chemical Oxidation and Biological Funneling

Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of these materials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either ..beta..-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on HgTe(HO)7 by Materials Project

HgH5TeO6H2O crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of two water molecules and one HgH5TeO6 ribbon oriented in the (0, 1, 1) direction. In the HgH5TeO6 ribbon, Hg1+ is bonded in a distorted single-bond geometry to one O2- atom. The Hg–O bond length is 2.18 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.64 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are two inequivalent Te6+ sites. In the first Te6+ site, Te6+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Te–O bond distances ranging from 1.93–1.98 Å. In the second Te6+ site, Te6+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Te–O bond distances ranging from 1.90–2.02 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one Te6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one H1+ and one Te6+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Te6+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to one Hg1+, one H1+, and one Te6+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one H1+ and one Te6+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one Te6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrN7ClO6 by Materials Project

IrN3O6Cl(N2)2 crystallizes in the tetragonal I4 space group. The structure is two-dimensional and consists of eight ammonia molecules and two IrN3O6Cl sheets oriented in the (0, 0, 1) direction. In each IrN3O6Cl sheet, Ir4+ is bonded in a distorted single-bond geometry to one N+1.29+ and one Cl1- atom. The Ir–N bond length is 1.72 Å. The Ir–Cl bond length is 2.63 Å. There are two inequivalent N+1.29+ sites. In the first N+1.29+ site, N+1.29+ is bonded in a single-bond geometry to one Ir4+ atom. In the second N+1.29+ site, N+1.29+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.25 Å) and one longer (1.26 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one N+1.29+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one N+1.29+ and one Cl1- atom. The O–Cl bond length is 3.32 Å. Cl1- is bonded in a distorted square pyramidal geometry to one Ir4+ and four equivalent O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PtN4(ClO)2 by Materials Project

Pt(N2OCl)2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of two platinum molecules and four N2OCl ribbons oriented in the (0, 1, 0) direction. In each N2OCl ribbon, N1+ is bonded in a distorted single-bond geometry to one O2- and one Cl1- atom. The N–O bond length is 1.39 Å. The N–Cl bond length is 2.13 Å. O2- is bonded in a water-like geometry to two equivalent N1+ atoms. Cl1- is bonded in a 2-coordinate geometry to two equivalent N1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H5CSO5F3 by Materials Project

(CF3)2(H2O)4(HSO2)2O2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four fluoroform molecules; two hydrogen peroxide molecules; eight water molecules; and two HSO2 ribbons oriented in the (1, 0, 0) direction. In each HSO2 ribbon, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.65 Å) H–O bond length. S4+ is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.49 Å) and one longer (1.61 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one H1+ and one S4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one H1+ and one S4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsC3S3NF10 by Materials Project

CAsNS3F6(CF2)2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of eight difluoromethane molecules and two CAsNS3F6 ribbons oriented in the (0, 1, 0) direction. In each CAsNS3F6 ribbon, C4+ is bonded in a distorted single-bond geometry to one N1- and one S2- atom. The C–N bond length is 1.29 Å. The C–S bond length is 1.75 Å. As5+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.76–1.82 Å. N1- is bonded in a distorted bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.60 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a single-bond geometry to one N1- and one S2- atom. The S–S bond length is 2.12 Å. In the second S2- site, S2- is bonded in a 1-coordinate geometry to two S2- and three F1- atoms. The S–S bond length is 2.04 Å. There are a spread of S–F bond distances ranging from 2.68–3.28 Å. In the third S2- site, S2- is bonded in a 1-coordinate geometry to one C4+ and one S2- atom. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to one As5+ and one S2- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one As5+ and one S2- atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one As5+ and one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

An Integrated Theoretical and Experimental Approach to Achieve Highly Polarizable Relaxor Ferroelectric Liquid Crystalline Polymers

In this project, we have designed and synthesized a series of aliphatic sulfonlyated chiral and achiral polyether. The major objective is to achieve ferroelectric liquid crystalline polymers with a high spontaneous polarization (0.04-0.08 C/m2). Due to the strong dipole-dipole interaction among the sulfonyl side groups, which resembles that among water molecules, these polyethers can exhibit various liquid crystalline self-assemblies without any rigid mesogens. By tuning the position of the sulfonyl groups, single versus double sulfonyl groups, and spacer/tail length and methyl branches, the liquid crystalline phases include smectic A, smectic C, and hexagonal columnar phases. When the single sulfonyl group is next to the main chain or disulfonyl groups are separated by a short C3 spacer, the dipolar interaction is too strong to allow any dipole switching. As a result, the linear dielectric behavior is observed with a low dielectric constant of 5-7. When the single sulfonyl groups are away from the main chain, the paraelectric behavior is obtained with a high dielectric constant around 20. From this study, we predict that by further tailoring the intermolecular interactions among the disulfonyl side groups, it is possible to achieve ferroelectric property for these liquid crystalline polymers. If successful, these ferroelectric liquid crystalline polymers can be used for efficient electrocaloric cooling applications.

36 MATERIALS SCIENCE↗