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Maximo Baron

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Mohammed Musa Lawan, Ph.D.

University of Aberdeen

Augustine Okhamafe

University of Benin

Universitat Politecnica de Catalunya

International Journal for Pharmaceutical Research Scholars (IJPRS)

Agricultural University of Plovdiv

Monash University (Malaysia)

Maria Angeles Pajares Tarancon

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

Ahmad Rohi Ghazali

Universiti Kebangsaan Malaysia

University of Western Ontario

Prof. Palash Mandal

CHAROTAR UNIVERSITY OF SCIENCE AND TECHNOLOGY-CHANGA

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Papers by Maximo Baron

Dielectric constant of binary systems. I: An apparent anomaly in the behaviour of ϵ for mixtures of benzene derivatives: Part of this subject matter was presented at the 52nd. Meeting of the asociación física Argentina, July 30, 1969. La Plata, Argentina

Recueil des Travaux Chimiques des Pays-Bas, 2010

The structure of α-parabutylchloral

Recueil des Travaux Chimiques des Pays-Bas, 2010

ABSTRACT The structure of α-parabutylchloral was reexamined on the basis of the NMR spectra at ro... more

Structure of malic acid chloralide

Recueil des Travaux Chimiques des Pays-Bas, 2010

The structure of malic acid chloralide was studied by N.M.R. and found to be a 1,3-dioxolan-4-one... more The structure of malic acid chloralide was studied by N.M.R. and found to be a 1,3-dioxolan-4-one. During our work on cyclic derivatives of chlorinated aldehydes 1l a question was raised regarding the structure of malic acid chloralide I (2-methylcarboxy-5-trichloromethyl-1,3-dioxolan-4-one). This compound is obtained by reacting malic acid with chloral hydrate at room temp. in the presence of conc. H2SO4 3. As can be seen in Fig. 1, there are two possible ways for the reaction to proceed: to give a compound of formula I or 11. Although this problem had already received some attention by Jones no definite answer has been given so far. An N.M.R. spectrum of this chloralide (see Table 1) presented a rather unusual feature: all the peaks show what appears to be a coupling of J = 1.5 cps. This seemed especially strange because it would imply a coupling * Part of this subject was presented at the Kekule-Symposium held in Lima (Peru)

Vapor-phase dipole moment values from solution measurements

The Journal of Physical Chemistry, 1985

to dichloroacetate. The degree of counterion dissociation is largest for decylammonium acetate an... more to dichloroacetate. The degree of counterion dissociation is largest for decylammonium acetate and therefore the negative entropy contribution is reduced to a higher degree when increasing the surfactant concentration. Conclusions It is demonstrated that the Fourier transform NMR self-diffusion technique gives direct and easy access to information on organic counterion binding to micelles even in the presence of several counterions. The degree of counterion binding, the cmc, and the free amphiphile concentration above cmc were demonstrated to be distinctly different for decylammonium acetate, chloroacetate, and dichloroacetate. In a competitive situation, an amplification of the differences in ion binding was demonstrated.

Structure of 2,4,6-trialkylsubstituted 1,3,5-trioxans

Recueil des Travaux Chimiques des Pays-Bas, 2010

Improved optical chamber for small measuring cells with temperature control

Review of Scientific Instruments, 2005

An improved optical chamber is described containing a Chatelain prism with controlled heating and... more

Ab Initio and in-Crystal Geometry of trans-1,4-Dibromo1,4-dicarboxymethylcyclohexane

Structural Chemistry, 2000

The structure of trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (I) has been determined by sing... more The structure of trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (I) has been determined by single crystal x-ray diffraction. The molecules, located on symmetry centers, are in the rigid chair conformation with the Br and COOCH3 axial and equatorial, respectively. The molecular geometry observed in the crystal is similar to that calculated for the isolated molecule using ab initio calculations performed at the HF/6-31(d) level. A

Action of a weak static magnetic field on a family of nematic liquid crystals as starting point for the study of this effect on biological membranes. Máximo Barón & Verónica Y. Adaro

Liquid Crystals - Web edition, 2014

ABSTRACT Long-range ordered molecular systems, such as many biological intracellular membranes, a... more ABSTRACT Long-range ordered molecular systems, such as many biological intracellular membranes, are related to problems of human health and can be affected by physical effects such as electric and magnetic. To study the effect of low-intensity static magnetic fields (B) and temperature (K) could be recorded over the whole mesophases. Three-dimensional plots (ne vs B vs K) indicated a distinct behaviour in the ne depending on the chain length of the alkyl substituent. This suggests that this procedure could be useful to examine the effect of weak static magnetic fields on liquid crystalline like molecular systems, especially those of biological interest.

Dielectric properties of binary systems. 7. Carbon tetrachloride with benzene, with toluene, and with p-xylene at 298.15 and 308.15 K

The Journal of Physical Chemistry, 1988

than the two-step procedures, making available very homogeneous composite films. The analysis of ... more than the two-step procedures, making available very homogeneous composite films. The analysis of the electrochemical behavior of these films shows that, in the same way as their electrical and optical properties, their electroactivity depends strongly on the synthesis conditions and can thus be controlled by this way. The large possibilities offered by the one-step technique could be applied to the realization of solid-state all-polymeric batteries based on composite materials containing electronically and ionically conducting polymers which would result in a solid-state interface22 with enhanced contacting area. On the other hand,

The Liquid Water−Benzene System

The Journal of Physical Chemistry A, 2006

The 500 MHz NMR spectra of water-benzene solution near saturation at 303.15, 323.15, and 343.15 K... more The 500 MHz NMR spectra of water-benzene solution near saturation at 303.15, 323.15, and 343.15 K indicate that there is a proton-proton exchange between the water and benzene molecules. In the solution water appears to be present as a dimer attached to the benzene π cloud on one side of each of the two (initially degenerate) fundamental energy levels, as predicted by the Jahn-Teller effect. This view is reinforced by the fact that one of its hydrogen atoms hovers above one of the carbon atoms and the other three are spread upward around the C6 axis of the benzene molecule. It is also supported by the calculated NMR spectra. Both effects are responsible for the change in the NMR spectra of the water molecules from a single line into four AB signals.

Interconversion Study in 1,4-Substituted Six-Membered Cyclohexane-Type Rings. Structure and Dynamics of trans -1,4-Dibromo-1,4-dicyanocyclohexane

The Journal of Physical Chemistry A, 2011

Temperature control in small air-heated measuring cells

Review of Scientific Instruments, 1990

ABSTRACT Temperature control in a liquid sample contained in a Chatelain prism was achieved in a ... more

Glossary of class names of polymers based on chemical structure and molecular architecture (IUPAC Recommendations 2009)

Pure and Applied Chemistry, 2009

This document defines class names of polymers based on the class names of starting monomers and c... more This document defines class names of polymers based on the class names of starting monomers and characteristic features of the chemical constitution of polymer molecules (macromolecules), i.e., class names that have gained general acceptance in the polymer and material literature, science and technology as well as in public. The glossary is divided into three parts: Source-based class names, which identify common classes of starting monomers such as "acrylic", "diene", "phenolic", "vinylic". Class names based on chemical structure, which identify characteristic groups in the main chains (backbones) of the polymer molecules such as (i) inter-unit groups derived from functional groups, e.g., "amide", "ester", "ether"; (ii) a specific group of atoms, e.g., "alkenylene", "siloxane", "sulfone"; (iii) ring structures, e.g., "benzimidazole", "benzoxazole", "quinoxali...

Definitions relating to stereochemically asymmetric polymerizations (IUPAC Recommendations 2001)

Pure and Applied Chemistry, 2002

Asymmetric polymerization has been of interest to many academic and industrial polymer scientists... more Asymmetric polymerization has been of interest to many academic and industrial polymer scientists, but no reference has been made by IUPAC explicitly to classification and definitions of reactions involving the asymmetric synthesis of polymers. This document presents definitions concerned with asymmetric and related polymerizations, with examples included to clarify the meaning of the definitions. Asymmetric polymerizations embrace two main categories, "asymmetric chirogenic polymerizations" and "asymmetric enantiomer-differentiating polymerizations".

Definitions of terms relating to reactions of polymers and to functional polymeric materials (IUPAC Recommendations 2003)

Pure and Applied Chemistry, 2004

The document defines the terms most commonly encountered in the field of polymer reactions and fu... more The document defines the terms most commonly encountered in the field of polymer reactions and functional polymers. The scope has been limited to terms that are specific to polymer systems. The document is organized into three sections. The first defines the terms relating to reactions of polymers. Names of individual chemical reactions are omitted from the document, even in cases where the reactions are important in the field of polymer reactions. The second section defines the terms relating to polymer reactants and reactive polymeric materials. The third section defines the terms describing functional polymeric materials.

Chirality in trans-1,4-cyclohexane dicarboxylic acid

Journal of Molecular Structure, 1990

The existence of chiral geometries of trans-1,4cyclohexane dicarhoxylic acid, both in the solid s... more

Unexpected chirality in trans-1,4-dicyanocyclohexane

Journal of Molecular Structure, 1988

The experimental non-zero dipole moment of trans-1,4-dicyanocyclohexane was verified through a pr... more The experimental non-zero dipole moment of trans-1,4-dicyanocyclohexane was verified through a procedure little sensitive to solute/solvent interactions. This value cannot be explained on the basis of the generally accepted centrosymmetry for frans-1,4derivatives of cyclohexane. NMR data of both this compound and its C-l, C-4 di-deuteroderivative, as well as semiempirical theoretical calculations with the MNDO methods show that besides a centrosymmetric form there are also low energy stable non-centrosymmetric geometries. The latter exist as a helical deformation that can account for the non-zero value of the experimental dipole moment. *Members of the Carrera de1 Investigador.

$Research paper thumbnail of Influence of weak magnetic fields on the extraordinary refractive index of two cyanoalkylbiphenyls$

Influence of weak magnetic fields on the extraordinary refractive index of two cyanoalkylbiphenyls

Journal of Molecular Liquids, 1994

ABSTRACT Changes in the extraordinary refractive indices of 4-cyano-4&#39;-n-pentylbiphenyl (... more ABSTRACT Changes in the extraordinary refractive indices of 4-cyano-4&#39;-n-pentylbiphenyl (5CB) and 4-cyano-4&#39;-n-heptylbiphenyl (7CB) were measured, in their liquid crystalline mesophase, as a function of temperature, (T) and weak constant magnetic field (B) (0–600 gauss). The field was applied parallel to the optical axis of the sample. Chatelain&#39;s prism was used as measuring cell, for a total of 500 measurements.The slopes of the extraordinary (ne) and the ordinary (no) refractive indices were examined as a function of temperature and magnetic field (T and B). As expected from previous work (1, 2), ne vs T was found to be negative. Consequently, there also seems to be a competition between the disorder created by temperature (internal movements, deformation and molecular rotations) and the orientational effect of the rubbed glass plates of the measuring cell, reinforced by the parallel magnetic field. On the other hand the slope ne(T) vs B (Figure) shows an anomalous behaviour in the low field region (100–400 gauss), with no explanation available yet.

Liquid crystal birefringence and electric dipole moment relationship with temperature, weak magnetic field and molecular geometry

Journal of Molecular Liquids, 1989

ABSTRACT Birefringence in the mesophase of 4-cyano-4′-n-pentylbiphenyl (5CB) was measured directl... more ABSTRACT Birefringence in the mesophase of 4-cyano-4′-n-pentylbiphenyl (5CB) was measured directly under a magnetic field (1200 and 2000 gauss) as a function of temperature with field parallel and perpendicular to the optical axis. Electrical dinole moments of 5CB and benzonitrile were calculated with the Mechetti-Barón equations from measurements at three temperatures. Molecular geometries were examined with a semiempirical procedure (AMPAC).The results suqgest that thermal stirring and internal rotations appear to overcome orientational effects of the applied field.

Dielectric properties of binary systems 8. Improved model for alcohol/non polar systems

Journal of Molecular Liquids, 1988

... MARIA BERTA REBOLLO PAZ, ADRIAN HUGO BUEP AND MAXIMO BARON Departamento de Fisica, Facultad d... more

Dielectric constant of binary systems. I: An apparent anomaly in the behaviour of ϵ for mixtures of benzene derivatives: Part of this subject matter was presented at the 52nd. Meeting of the asociación física Argentina, July 30, 1969. La Plata, Argentina

Recueil des Travaux Chimiques des Pays-Bas, 2010

The structure of α-parabutylchloral

Recueil des Travaux Chimiques des Pays-Bas, 2010

ABSTRACT The structure of α-parabutylchloral was reexamined on the basis of the NMR spectra at ro... more

Structure of malic acid chloralide

Recueil des Travaux Chimiques des Pays-Bas, 2010

The structure of malic acid chloralide was studied by N.M.R. and found to be a 1,3-dioxolan-4-one... more The structure of malic acid chloralide was studied by N.M.R. and found to be a 1,3-dioxolan-4-one. During our work on cyclic derivatives of chlorinated aldehydes 1l a question was raised regarding the structure of malic acid chloralide I (2-methylcarboxy-5-trichloromethyl-1,3-dioxolan-4-one). This compound is obtained by reacting malic acid with chloral hydrate at room temp. in the presence of conc. H2SO4 3. As can be seen in Fig. 1, there are two possible ways for the reaction to proceed: to give a compound of formula I or 11. Although this problem had already received some attention by Jones no definite answer has been given so far. An N.M.R. spectrum of this chloralide (see Table 1) presented a rather unusual feature: all the peaks show what appears to be a coupling of J = 1.5 cps. This seemed especially strange because it would imply a coupling * Part of this subject was presented at the Kekule-Symposium held in Lima (Peru)

Vapor-phase dipole moment values from solution measurements

The Journal of Physical Chemistry, 1985

to dichloroacetate. The degree of counterion dissociation is largest for decylammonium acetate an... more to dichloroacetate. The degree of counterion dissociation is largest for decylammonium acetate and therefore the negative entropy contribution is reduced to a higher degree when increasing the surfactant concentration. Conclusions It is demonstrated that the Fourier transform NMR self-diffusion technique gives direct and easy access to information on organic counterion binding to micelles even in the presence of several counterions. The degree of counterion binding, the cmc, and the free amphiphile concentration above cmc were demonstrated to be distinctly different for decylammonium acetate, chloroacetate, and dichloroacetate. In a competitive situation, an amplification of the differences in ion binding was demonstrated.

Structure of 2,4,6-trialkylsubstituted 1,3,5-trioxans

Recueil des Travaux Chimiques des Pays-Bas, 2010

Improved optical chamber for small measuring cells with temperature control

Review of Scientific Instruments, 2005

An improved optical chamber is described containing a Chatelain prism with controlled heating and... more

Ab Initio and in-Crystal Geometry of trans-1,4-Dibromo1,4-dicarboxymethylcyclohexane

Structural Chemistry, 2000

The structure of trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (I) has been determined by sing... more The structure of trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (I) has been determined by single crystal x-ray diffraction. The molecules, located on symmetry centers, are in the rigid chair conformation with the Br and COOCH3 axial and equatorial, respectively. The molecular geometry observed in the crystal is similar to that calculated for the isolated molecule using ab initio calculations performed at the HF/6-31(d) level. A

Action of a weak static magnetic field on a family of nematic liquid crystals as starting point for the study of this effect on biological membranes. Máximo Barón & Verónica Y. Adaro

Liquid Crystals - Web edition, 2014

ABSTRACT Long-range ordered molecular systems, such as many biological intracellular membranes, a... more ABSTRACT Long-range ordered molecular systems, such as many biological intracellular membranes, are related to problems of human health and can be affected by physical effects such as electric and magnetic. To study the effect of low-intensity static magnetic fields (B) and temperature (K) could be recorded over the whole mesophases. Three-dimensional plots (ne vs B vs K) indicated a distinct behaviour in the ne depending on the chain length of the alkyl substituent. This suggests that this procedure could be useful to examine the effect of weak static magnetic fields on liquid crystalline like molecular systems, especially those of biological interest.

Dielectric properties of binary systems. 7. Carbon tetrachloride with benzene, with toluene, and with p-xylene at 298.15 and 308.15 K

The Journal of Physical Chemistry, 1988

than the two-step procedures, making available very homogeneous composite films. The analysis of ... more than the two-step procedures, making available very homogeneous composite films. The analysis of the electrochemical behavior of these films shows that, in the same way as their electrical and optical properties, their electroactivity depends strongly on the synthesis conditions and can thus be controlled by this way. The large possibilities offered by the one-step technique could be applied to the realization of solid-state all-polymeric batteries based on composite materials containing electronically and ionically conducting polymers which would result in a solid-state interface22 with enhanced contacting area. On the other hand,

The Liquid Water−Benzene System

The Journal of Physical Chemistry A, 2006

The 500 MHz NMR spectra of water-benzene solution near saturation at 303.15, 323.15, and 343.15 K... more The 500 MHz NMR spectra of water-benzene solution near saturation at 303.15, 323.15, and 343.15 K indicate that there is a proton-proton exchange between the water and benzene molecules. In the solution water appears to be present as a dimer attached to the benzene π cloud on one side of each of the two (initially degenerate) fundamental energy levels, as predicted by the Jahn-Teller effect. This view is reinforced by the fact that one of its hydrogen atoms hovers above one of the carbon atoms and the other three are spread upward around the C6 axis of the benzene molecule. It is also supported by the calculated NMR spectra. Both effects are responsible for the change in the NMR spectra of the water molecules from a single line into four AB signals.

Interconversion Study in 1,4-Substituted Six-Membered Cyclohexane-Type Rings. Structure and Dynamics of trans -1,4-Dibromo-1,4-dicyanocyclohexane

The Journal of Physical Chemistry A, 2011

Temperature control in small air-heated measuring cells

Review of Scientific Instruments, 1990

ABSTRACT Temperature control in a liquid sample contained in a Chatelain prism was achieved in a ... more

Glossary of class names of polymers based on chemical structure and molecular architecture (IUPAC Recommendations 2009)

Pure and Applied Chemistry, 2009

This document defines class names of polymers based on the class names of starting monomers and c... more This document defines class names of polymers based on the class names of starting monomers and characteristic features of the chemical constitution of polymer molecules (macromolecules), i.e., class names that have gained general acceptance in the polymer and material literature, science and technology as well as in public. The glossary is divided into three parts: Source-based class names, which identify common classes of starting monomers such as "acrylic", "diene", "phenolic", "vinylic". Class names based on chemical structure, which identify characteristic groups in the main chains (backbones) of the polymer molecules such as (i) inter-unit groups derived from functional groups, e.g., "amide", "ester", "ether"; (ii) a specific group of atoms, e.g., "alkenylene", "siloxane", "sulfone"; (iii) ring structures, e.g., "benzimidazole", "benzoxazole", "quinoxali...

Definitions relating to stereochemically asymmetric polymerizations (IUPAC Recommendations 2001)

Pure and Applied Chemistry, 2002

Asymmetric polymerization has been of interest to many academic and industrial polymer scientists... more Asymmetric polymerization has been of interest to many academic and industrial polymer scientists, but no reference has been made by IUPAC explicitly to classification and definitions of reactions involving the asymmetric synthesis of polymers. This document presents definitions concerned with asymmetric and related polymerizations, with examples included to clarify the meaning of the definitions. Asymmetric polymerizations embrace two main categories, "asymmetric chirogenic polymerizations" and "asymmetric enantiomer-differentiating polymerizations".

Definitions of terms relating to reactions of polymers and to functional polymeric materials (IUPAC Recommendations 2003)

Pure and Applied Chemistry, 2004

The document defines the terms most commonly encountered in the field of polymer reactions and fu... more The document defines the terms most commonly encountered in the field of polymer reactions and functional polymers. The scope has been limited to terms that are specific to polymer systems. The document is organized into three sections. The first defines the terms relating to reactions of polymers. Names of individual chemical reactions are omitted from the document, even in cases where the reactions are important in the field of polymer reactions. The second section defines the terms relating to polymer reactants and reactive polymeric materials. The third section defines the terms describing functional polymeric materials.

Chirality in trans-1,4-cyclohexane dicarboxylic acid

Journal of Molecular Structure, 1990

The existence of chiral geometries of trans-1,4cyclohexane dicarhoxylic acid, both in the solid s... more

Unexpected chirality in trans-1,4-dicyanocyclohexane

Journal of Molecular Structure, 1988

The experimental non-zero dipole moment of trans-1,4-dicyanocyclohexane was verified through a pr... more The experimental non-zero dipole moment of trans-1,4-dicyanocyclohexane was verified through a procedure little sensitive to solute/solvent interactions. This value cannot be explained on the basis of the generally accepted centrosymmetry for frans-1,4derivatives of cyclohexane. NMR data of both this compound and its C-l, C-4 di-deuteroderivative, as well as semiempirical theoretical calculations with the MNDO methods show that besides a centrosymmetric form there are also low energy stable non-centrosymmetric geometries. The latter exist as a helical deformation that can account for the non-zero value of the experimental dipole moment. *Members of the Carrera de1 Investigador.

$Research paper thumbnail of Influence of weak magnetic fields on the extraordinary refractive index of two cyanoalkylbiphenyls$

Influence of weak magnetic fields on the extraordinary refractive index of two cyanoalkylbiphenyls

Journal of Molecular Liquids, 1994

ABSTRACT Changes in the extraordinary refractive indices of 4-cyano-4&#39;-n-pentylbiphenyl (... more ABSTRACT Changes in the extraordinary refractive indices of 4-cyano-4&#39;-n-pentylbiphenyl (5CB) and 4-cyano-4&#39;-n-heptylbiphenyl (7CB) were measured, in their liquid crystalline mesophase, as a function of temperature, (T) and weak constant magnetic field (B) (0–600 gauss). The field was applied parallel to the optical axis of the sample. Chatelain&#39;s prism was used as measuring cell, for a total of 500 measurements.The slopes of the extraordinary (ne) and the ordinary (no) refractive indices were examined as a function of temperature and magnetic field (T and B). As expected from previous work (1, 2), ne vs T was found to be negative. Consequently, there also seems to be a competition between the disorder created by temperature (internal movements, deformation and molecular rotations) and the orientational effect of the rubbed glass plates of the measuring cell, reinforced by the parallel magnetic field. On the other hand the slope ne(T) vs B (Figure) shows an anomalous behaviour in the low field region (100–400 gauss), with no explanation available yet.

Liquid crystal birefringence and electric dipole moment relationship with temperature, weak magnetic field and molecular geometry

Journal of Molecular Liquids, 1989

ABSTRACT Birefringence in the mesophase of 4-cyano-4′-n-pentylbiphenyl (5CB) was measured directl... more ABSTRACT Birefringence in the mesophase of 4-cyano-4′-n-pentylbiphenyl (5CB) was measured directly under a magnetic field (1200 and 2000 gauss) as a function of temperature with field parallel and perpendicular to the optical axis. Electrical dinole moments of 5CB and benzonitrile were calculated with the Mechetti-Barón equations from measurements at three temperatures. Molecular geometries were examined with a semiempirical procedure (AMPAC).The results suqgest that thermal stirring and internal rotations appear to overcome orientational effects of the applied field.

Dielectric properties of binary systems 8. Improved model for alcohol/non polar systems

Journal of Molecular Liquids, 1988

... MARIA BERTA REBOLLO PAZ, ADRIAN HUGO BUEP AND MAXIMO BARON Departamento de Fisica, Facultad d... more