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We investigate the nematic (N) to twist-bend nematic (NTB) phase transition in binary mixtures of a symmetric liquid crystal dimer (CB7CB) and a calamitic bi-phenyl mesogen (7OCB). As the molar concentration of 7OCB increases, both the Iso–N and N–NTB transition temperatures decrease gradually, consequently, the width of the nematic phase above the NTB phase can suitably be varied from ~12 K to 46 K. Notably, as the nematic range expands, there is a remarkable reduction in transitional entropy, eventually approaching negligible or zero values. Additionally, the heat capacity peak and the phase shift disappear when transitional entropy reaches zero. This behaviour diverges from typical N–SmA and N–SmC phase transitions, where transitional entropy decreases near the tricritical point but the heat capacity peak persists. Our findings indicate a finite positive δ(∆n) across all concentrations at the N–NTB phase transition, suggesting a gradually weakening first-order nature. This contrasts with theoretical predictions of a second-order N–NTB phase transition, as our experimental data consistently supports a first-order nature. The self-consistent mean-field Landau Model successfully validates our experimental data, establishing the universal first-order nature of the N–NTB phase transition, with experimental entropy values in good agreement with theoretical prediction. [ABSTRACT FROM AUTHOR]

Frustrated phases in chiral liquid crystalline systems, such as the blue phase (BP) and the twist grain boundary (TGB) phase, can create new opportunities in liquid crystal research. These frustrated phases have unique optical properties which can be used for specific applications. A new binary mixture system composed of a chiral rod-like ferroelectric liquid crystal and an achiral hockey stick-shaped compound was designed. This binary system exhibits induced frustration, resulting in the emergence of the BP-III and TGBA* phases in addition to the chiral ferroelectric Smectic-C* phase. We report a comprehensive study on several binary mixtures (xH-22.5= 0.162, 0.25, 0.396, 0.562) designed of a chiral ferroelectric liquid crystal derived from the lactic acid, namely 4-(octyloxy)phenyl 3-methoxy-4-((4-((2-(pentyloxy)propanoyl)oxy)benzoyl)oxybenzoate and achiral hockey stick-shaped compound, namely (E)-4-((E-((3-(decyloxy)-2-methylphenyl)imino)methyl)-phenyl 3-(4-(dodecyloxy)phenyl)acrylate. These mixtures induced the blue phase (BP-III, ~2.5-6.2K) and the twist grain boundary Smectic-A*phase (TGBA* ~1.8-6K). Polarizing optical microscopy, birefringence, and dielectric spectroscopy were employed to investigate the BPIII and TGBA* phases, as those techniques provide insights into their structural and dynamic properties. The ferroelectric behaviour of the SmC* mesophase was investigated by electrooptics. The obtained results are discussed in relation to the molecular structures of the used materials. [ABSTRACT FROM AUTHOR]

The study focused on the binary system 6OCB and 8OCB, which is well-suited for investigating stable re-entrant nematic-phase transitions. High-resolution measurements of heat capacity and birefringence are used to analyse critical behaviours near the nematic – smectic-A (N-SmA) and the smectic-A – re-entrant nematic (SmA- ${{\rm{N}}_{\rm{R}}}$ N R ) phase transitions. The critical behaviour of these transitions has been explored with the aid of a differential quotient extracted from the birefringence $\left({\rm \Delta {{n}}} \right)$ Δ n values. Simultaneously, critical exponents extracted from the specific heat capacity anomaly are also used to analyse the critical behaviour of the phase transition. The results indicate that the SmA to ${{\rm{N}}_{\rm{R}}}$ N R phase transition exhibits non-universal behaviour, with effective exponents falling between the tricritical (TCP) and 3D-XY values, similar to the N-SmA phase transition. The study reveals the existence of two tricritical points: one associated with the N-SmA transition and the other corresponding to the SmA- ${{\rm{N}}_{\rm{R}}}$ N R transition. This is supported by plotting the McMillan ratio against the critical exponents obtained from both birefringence and specific heat capacity anomaly. Again, with an increase in the SmA range, the SmA- ${{\rm{N}}_{\rm{R}}}$ N R transition tends towards the tricritical point (TCP), suggesting a relationship between the SmA range and the transitional behaviour. [ABSTRACT FROM AUTHOR]

We present a systematic experimental dataset on the temperature dependence of specific heat capacity in a binary mixture of the second and seventh homologous series of 5-alkyloxy-2-(4-nonyloxy-phenyl) pyrimidine (PhP) liquid crystal compound. These binary mixtures exhibit nematic, smectic-A, and smectic-C phases within a concentration range of x PhP1 = 0-0.45. The liquid crystalline phases are structurally characterized using synchrotron x-ray diffraction. We determine the apparent molecular length in the nematic phase, smectic layer spacing, average distance between the long axes of molecules, correlation length, and orientational order parameters (< P 2 > and < P 4 >) as functions of temperature. The tilt angle in the SmC phase is inferred from the layer spacing data. To examine the critical behavior near the nematic to smectic A (NA) and smectic A to the smectic C (AC) phase transitions, we evaluate the critical exponents: α from specific heat capacity, β from the fitting of the temperature-dependent tilt angle, and ν ǁ , ν ⊥ from the temperature-dependent longitudinal ( ξ ǁ ) and transverse ( ξ ⊥ ) correlation lengths. Modulated Differential Scanning Calorimetry (MDSC) measurements indicate the absence of phase shift, latent heat and imaginary specific heat capacity, suggesting that the AC transitions are second-order for all binary mixtures. The results obtained from heat capacity reveal that both the AC and NA transitions exhibit non-universal behaviors with effective exponents lying between the tricritical and 3D-XY values and follow nearly identical curve with decreasing width of the Sm-A and N phases. The Josephson hyper scaling relation is verified for both the NA and AC transitions in different mixtures. Moreover, knowing the heat capacity critical exponent α and the order parameter critical exponent β , the susceptibility critical exponent γ for the AC transition can be estimated from Rushbrooke equality α + 2 β + γ = 2, with γ values ranging from 1.015 to 1.313, indicating the system's crossover character and apparently validating the Rushbrooke equality., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Our present study intended to investigate the encapsulation of DL-AGT within the lipophilic cavity of a β-CD molecule. The consequential inclusion system was characterized by UV-visible spectroscopy and 1 H NMR, PXRD, SEM, and FT-IR studies. Molecular docking was performed for the inclusion complex to discover the most proper orientation, and it was seen that the drug DL-AGT fits into the cavity of β-CD in a 1:1 ratio, which was also confirmed from the Job plot. Furthermore, a comparison was done on the basis of cell viability between the drug and its inclusion complex., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)