Crystallization kinetics study on N-(p-n-alkyloxybenzylidene)-p-n-alkylanilines (nO.m compounds)

Kumar, P. A.; Mohan, M. L. N. Madhu; Pisipati, V. G. K. M.

doi:10.1080/026782900202192

Cited by 22 publications

(11 citation statements)

References 8 publications

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“…The kineto phase which occurs prior to the crystallization is solely responsible for many combinational factors of the crystallization mechanism. In the present study of 16A+11BA and 16A+12BA complexes the kineto phase prior to crystallization is Smectic G. Our previous studies [5,6,10,11] on different nO.m compounds exhibiting various kineto phases concurred with data of the present investigations. Further in Smectic G, as expected, the rate of crystallization is rapid as it is close to crystalline phase.…”

Section: The Process Of Crystallizationsupporting

confidence: 81%

“…From the figure 7 it can be inferred that the growth mechanism follows a uniform trend for all the temperature studied in the present compounds. Further more, crystallization kinetics data obtained by this technique for 16A+12BA compound at 45 o C, 46 o C and 48 o C are identical to those data obtained by DSC studies suggesting the existence of the same mechanism in the rate of crystallization kinetics [6]. …”

Section: Crystallization Kinetics Through Dielectric Studiessupporting

confidence: 73%

“…The inter molecular hydrogen bonded p-n-alkoxybenzoic acids (nABA) and hexadecylaniline liquid crystalline materials exhibits a fascinating mesomorphic behaviour associated with a distinct molecular ordering; the convenient working thermal range makes them suitable for systematic kinetic investigations. In continuation of our experimental studies [4][5][6][7][8][9][10][11] on liquid crystals here we present a detailed analysis of two smectogens of the hexadecylaniline series namely 16A+11BA and 16A+12BA. * Electronic address: mln.madhu@gmail.com…”

Section: Introductionmentioning

confidence: 99%

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Inter hydrogen bonded complexes of hexadecylaniline and alkoxy benzoic acids: a study of crystallization kinetics

Vijayakumar¹,

Murugadass²,

Mohan³

2009

Braz. J. Phys.

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A systematic crystallization kinetic study of two smectogens of homologous series of the inter molecular hydrogen bonded between undecyl, dodecyl benzoic acids and hexadecylaniline complexes viz., 16A+11BA and 16A+12BA respectively has been carried out by thermal microscopy, differential scanning calorimetry (DSC) and dielectric studies. FTIR studies indicate the formation of hydrogen bond in these complexes. The crystallization kinetics was studied by two techniques viz., the traditional thermal analysis (DSC) and electrical studies in which capacitance and dielectric loss variation with temperature were recorded and analyzed. The DSC thermograms were run from crystallization temperature to the isotropic melt for different time intervals. The liquid crystalline behaviour together with the rate of crystallization of smectic ordering in newly synthesized inter hydrogen bonded complexes were discussed in relation to the kinetophase (which occurs prior to the crystallization). The molecular mechanism and dimensionality in the crystal growth were computed from the Avrami equation. The characteristic crystallization time (t*) at each crystallization temperature was deduced from the individual plots of log t and ∆H. Further, it was observed that the data obtained from DSC and dielectric studies were in good agreement with one another. For the first time in the history of crystallization studies, crystallization kinetics data is experimentally elicited from a novel dielectric technique.

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Section: The Process Of Crystallizationsupporting

confidence: 81%

Section: Crystallization Kinetics Through Dielectric Studiessupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

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Inter hydrogen bonded complexes of hexadecylaniline and alkoxy benzoic acids: a study of crystallization kinetics

Vijayakumar¹,

Murugadass²,

Mohan³

2009

Braz. J. Phys.

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“…The investigations on crys tallization kinetics were perform ed on a Perkin-Elm er DSC7. The procedure for DSC scans perform ed at dif ferent crystallization tem peratures is reported in [13].…”

Section: Aterials and M Ethodsmentioning

confidence: 99%

Induced Smectic-G Phase through Intermolecular Hydrogen Bonding Part VIII: Phase and Crystallization Behaviours of 2-(p-n-heptyloxybenzyIidene imino)-5-chIoro-pyridine: p-n-alkoxybenzoic acid (HICP:n ABA) Complexes

Srinivasulu

Satyanarayana

Kumar

et al. 2001

Zeitschrift Für Naturforschung A

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New intermolecular H-bonded liquid crystalline complexes, viz., 2-(p-n-heptyloxybenzylidene imi-no)-5-chloro-pyridine:p-/z-alkoxybenzoic acid; (HICP:nABA) (where n denotes the alkoxy carbon num bers 3 to 10 and 12) exhibiting smectic-F (n = 12) and smectic-G phases have been synthesized and char acterized by Thermal Microscopy and Differential Scanning Calorimetry (DSC). Detailed IR (solid and solution states) analysis confirms the existence of intermolecular H-bonding between the pyridyl nitro gen and the COOH group of the p-n-alkoxybenzoic acid moiety. The phase behaviour of the series is discussed in the light of reported data on free p-n-alkoxybenzoic acids. The crystallization kinetics of a representative complex, using the DSC technique, is discussed. The mechanism of the crystal growth of the new crystalline smectic-G phase is computed with the Avrami equation.

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“…1) stand as potential candidates for the realization of a smectic-F phase along with other high temperature smectic phases. Our systematic and comprehensive studies on higher homologues of nO.m compounds exhibiting this unique phase variant [7][8][9][10][11][12] enable us to construct a typical plot (Fig. 2) on the basis of phase transition data (Table 1) …”

mentioning

confidence: 99%

Origin and Stabilization of Novel Single Phase Variant, Smectic-F Among nO.m Compounds

Pisipati

Kumar

Srinivasu

2002

Zeitschrift Für Naturforschung A

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Smectic and comprehensive investigations on the phase transition studies of p-n-alkoxybenzylidene-p-n-alkyl anilines (nO.m's) reveal the occurrence of direct smectic-F transition from isotropic liquid in higher homologues. We report the influence of terminal alkyl-and/or alkoxy-chain lengths on the manifestation and stabilization of this unique phase variant. Investigations on isotropic to liquid crystalline phase transitions, especially involving smectic phases, allow theoretical predictions [1] for the growth of 2D and 3D crystals from the isotropic liquid phase. The growth of a smectic-F phase from an isotropic liquid involves the formation of 2D structural order. In fact, very few compounds are reported that exhibit directly this transition [2][3][4]. The smectic-F phase with monoclinic symmetry and long-range tilt order, possessing a hexagonal molecular packing within the smectic layers (normal to the long axis of the molecules), has a quasi two-dimensional solid structure (i.e. poor correlation between layers). Materials exhibiting a 2D smectic ordering possessing a long-range bond orientational order with short-range tilted order [5] are important both in fundamental and applicational research, since piezoelectric response is reported [6] for the chiral version of the smectic-F phase. The isotropic to smectic-F phase transition involves the growth of an ordered tilted smectic phase.The higher homologues of p-n-alkoxybenzylidene-pn-alkyl anilines (commonly known as nO.m compounds) (Fig. 1) stand as potential candidates for the realization of a smectic-F phase along with other high temperature smectic phases. Our systematic and comprehensive studies on higher homologues of nO.m compounds exhibiting this unique phase variant [7][8][9][10][11][12] enable us to construct a typical plot (Fig. 2) on the basis of phase transition data (Table 1)

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Crystallization kinetics study on N-(p-n-alkyloxybenzylidene)-p-n-alkylanilines (nO.m compounds)

Cited by 22 publications

References 8 publications

Inter hydrogen bonded complexes of hexadecylaniline and alkoxy benzoic acids: a study of crystallization kinetics

Inter hydrogen bonded complexes of hexadecylaniline and alkoxy benzoic acids: a study of crystallization kinetics

Induced Smectic-G Phase through Intermolecular Hydrogen Bonding Part VIII: Phase and Crystallization Behaviours of 2-(p-n-heptyloxybenzyIidene imino)-5-chIoro-pyridine: p-n-alkoxybenzoic acid (HICP:n ABA) Complexes

Origin and Stabilization of Novel Single Phase Variant, Smectic-F Among nO.m Compounds

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