α-l-Glutamic acid under high pressure: Phase transitions studied by Raman spectroscopy

Luz-Lima, C.; Borges, J. A.; Moura, João Victor Barbosa; Pinheiro, G.S.; Viana, Bartolomeu C.; Mendes-Filho, J.; Freire, Paulo

doi:10.1016/j.vibspec.2016.08.012

Cited by 12 publications

(5 citation statements)

References 40 publications

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“…We attribute the abrupt increase in peak widths for 1468 and 3061 cm −1 Raman bands upon LT to HT transition to increased side chain disorder. Our inference is consistent with studies which showed that an abrupt increase in linewidth indicates onset of disorder in chemical bonds corresponding to the specific Raman shift 47 , 48 , 51 .…”

Section: Resultssupporting

confidence: 93%

Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors

et al. 2018

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Martensitic transition is a solid-state phase transition involving cooperative movement of atoms, mostly studied in metallurgy. The main characteristics are low transition barrier, ultrafast kinetics, and structural reversibility. They are rarely observed in molecular crystals, and hence the origin and mechanism are largely unexplored. Here we report the discovery of martensitic transition in single crystals of two different organic semiconductors. In situ microscopy, single-crystal X-ray diffraction, Raman and nuclear magnetic resonance spectroscopy, and molecular simulations combined indicate that the rotating bulky side chains trigger cooperative transition. Cooperativity enables shape memory effect in single crystals and function memory effect in thin film transistors. We establish a molecular design rule to trigger martensitic transition in organic semiconductors, showing promise for designing next-generation smart multifunctional materials.

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Section: Resultssupporting

confidence: 93%

Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors

et al. 2018

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“…Based on a combination of DFT calculations (Figure S6b) and literature, we assigned the peak at 1387 cm -1 to C=C stretching along the backbone, corresponding to the effective conjugation coordinate (ECC) mode for the quinoidal form [46][47][48] which we denote as ν(C=C) ECC,Q (Figure S6c, Movie S8,9); the peak at 1522 cm -1 was assigned to other C=C stretching modes in the backbone (Figure s6e, Movie s10); the peak at 1772 cm -1 was assigned to C=O stretching (Figure S6e, Movie S11). While the peak at 1409 cm -1 may correspond to core stretching (Figure S6d, Movie S12), this was assigned to CH 2 deformation in the alkyl chains denoted as δ(CH 2 ) based on wellestablished literature [49][50][51][52] on alkyl chain vibrations. Along with these peaks, we also tracked the peaks at 1025 and 1063 cm -1 which were assigned to C-C stretching of the trans ν(C-C) T and gauche ν(C-C) G isomers in the alkyl chains.…”

Section: Molecular Origin Of Transition Mechanismsmentioning

confidence: 99%

A Tale of Two Transitions: Unraveling Two Distinct Polymorph Transition Mechanisms in One n-Type Single Crystal for Dynamic Electronics

Davies

Park

Shiring

et al. 2021

Preprint

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Cooperativity is used by living systems to circumvent energetic and entropic barriers to yield highly efficient molecular processes. Cooperative structural transitions involve the simultaneous, concerted displacement of molecules in a crystalline material, in stark contrast to the more typical molecule-by-molecule nucleation and growth mechanism often breaking the single crystallinity. Cooperative transitions have acquired much attention in the research community for their low transition barriers, ultrafast kinetics, and structural reversibility. On the other hand, cooperative transitions are rarely observed in molecular crystals and the molecular origin is not well understood. Single crystals of 2-dimensional quinoidal terthiophene (2DQTT-o-B), a high-performance n-type organic semiconductor, demonstrate two thermally-activated, reversible phase transitions with one exhibiting a cooperative mechanism and the second exhibiting a nucleation and growth mechanism. In situ microscopy, single crystal and grazing incidence X-ray diffraction (GIXD), along with Raman spectroscopy suggest a reorientation of the alkyl side chains results in a cooperative transition behavior. On the other hand, the nucleation and growth transition is coincident with both side chain melting and the emergence of new spin-spin interactions between conjugated cores, confirmed through in situ electron paramagnetic resonance spectroscopy (EPR). This is the first observation of biradical interactions directly initiating a structural transition. Through studying these fundamental mechanisms, we establish alkyl chain conformation and disorder as integral to rationally controlling these polymorphic behaviors for novel electronic applications.

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Section: Resultsmentioning

confidence: 99%

“…Our inference agrees with previous studies, which illustrate that a broadening in the linewidth is related to increasing disorder in the chemical bonds related to the specific Raman shift. [41,42] Further investigation of the conformational transition of DPP-4T was conducted using UV-vis spectroscopy and atomic force microscopy (AFM) at different temperatures. As shown in Figure S7, Supporting Information, after heating to 533 K, the DPP-4T film exhibits a blue shift in signature 0-0 and 0-1 peaks due to the increased disorder of the molecular packing from thermal fluctuations.…”

Section: Temperature-dependent Molecular Packing Behaviormentioning

confidence: 99%

Molecular Packing and Charge Transport Behaviors of Semiconducting Polymers Over a Wide Temperature Range

Yang

Yan

et al. 2022

Adv Funct Materials

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The molecular packing and resultant charge transport behaviors of semiconducting polymers are widely known to be temperature‐dependent. Due to the limitation of measurement methods, previous studies on molecular packing behavior have been mainly focused on a very limited temperature range, and therefore cannot support the understanding of charge transport behaviors. In this study, with a homemade temperature‐dependent grazing incidence XRD measurement chamber, the relationship between molecular packing structure and charge transport properties of diketopyrrolopyrrole‐based polymers is investigated across a wide temperature range of 98–623 K. Glass transition temperatures of the alkyl side‐chain and aromatic backbone are identified through the observation of clear transitions in the thermal expansion coefficients of d−d packing and π−π stacking, respectively. A correlation between the π−π stacking distance and charge transport properties is then established using an extended Miller−Abrahams model. The turning point of the charge transport and the failure of the polymer‐based devices are proved to be caused by packing structure changes due to increased temperatures. Such an examination over a wide range of temperatures improves the understanding of the charge transport properties of semiconducting polymers and helps construct thermally stable devices to be used in extreme conditions.

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α-l-Glutamic acid under high pressure: Phase transitions studied by Raman spectroscopy

Cited by 12 publications

References 40 publications

Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors

Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors

A Tale of Two Transitions: Unraveling Two Distinct Polymorph Transition Mechanisms in One n-Type Single Crystal for Dynamic Electronics

Molecular Packing and Charge Transport Behaviors of Semiconducting Polymers Over a Wide Temperature Range

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