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© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

A polymorph of glycyl-L-alanine HI.H2O is synthesized from chiral cyclo-glycyl-L-alanine dipeptide. The dipeptide is known to show molecular flexibility in different environments, which leads to polymorphism. The crystal structure of the glycyl-L-alanine HI.H2O polymorph is determined at room temperature and indicates that the space group is polar (P21), with two molecules per unit cell and unit cell parameters a = 7.747 Å, b = 6.435 Å, c = 10.941 Å, α = 90°, β = 107.53(3)°, γ = 90° and V = 520.1(7) Å3. Crystallization in the polar point group 2, with one polar axis parallel to the b axis, allows pyroelectricity and optical second harmonic generation. Thermal melting of the glycyl-L-alanine HI.H2O polymorph starts at 533 K, close to the melting temperature reported for cyclo-glycyl-L-alanine (531 K) and 32 K lower than that reported for linear glycyl-L-alanine dipeptide (563 K), suggesting that although the dipeptide, when crystallized in the polymorphic form, is not anymore in its cyclic form, it keeps a memory of its initial closed chain and therefore shows a thermal memory effect. Here, we report a pyroelectric coefficient as high as 45 µC/m2K occurring at 345 K, one order of magnitude smaller than that of semi-organic ferroelectric triglycine sulphate (TGS) crystal. Moreover, the glycyl-L-alanine HI.H2O polymorph displays a nonlinear optical effective coefficient of 0.14 pm/V, around 14 times smaller than the value from a phase-matched inorganic barium borate (BBO) single crystal. The new polymorph displays an effective piezoelectric coefficient equal to deff=280 pCN1, when embedded into electrospun polymer fibers, indicating its suitability as an active system for energy harvesting.

Details

Title
A Polymorph of Dipeptide Halide Glycyl-L-Alanine Hydroiodide Monohydrate: Crystal Structure, Optical Second Harmonic Generation, Piezoelectricity and Pyroelectricity
Author
Baptista, Rosa M F 1   VIAFID ORCID Logo  ; Gomes, Clara S B 2   VIAFID ORCID Logo  ; Silva, Bruna 1   VIAFID ORCID Logo  ; Oliveira, João 1   VIAFID ORCID Logo  ; Almeida, Bernardo 1 ; Castro, Cidália 3   VIAFID ORCID Logo  ; Rodrigues, Pedro V 3   VIAFID ORCID Logo  ; Machado, Ana 3 ; Freitas, Ruben B 4   VIAFID ORCID Logo  ; Manuel J L F Rodrigues 1 ; Etelvina de Matos Gomes 1 ; Belsley, Michael 1   VIAFID ORCID Logo 

 Centre of Physics of Minho and Porto Universities (CF-UM-UP), Laboratory for Materials and Emergent Technologies (LAPMET), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; [email protected] (R.M.F.B.); [email protected] (B.S.); [email protected] (J.O.); [email protected] (B.A.); [email protected] (M.J.L.F.R.); [email protected] (E.d.M.G.) 
 LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; [email protected]; UCIBIO, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; i4HB, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal 
 Institute for Polymers and Composites, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; [email protected] (C.C.); [email protected] (P.V.R.); [email protected] (A.M.) 
 Department of Electronic Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal; [email protected] 
First page
3690
Publication year
2023
Publication date
2023
Publisher
MDPI AG
e-ISSN
19961944
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2819443644
Copyright
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.