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Papers by Mrityunjoy Mahato

Research paper thumbnail of The formation of pepsin monomolecular layer by the Langmuir–Blodgett film deposition technique

Colloids and Surfaces B-biointerfaces, 2009

We report herein the formation of pepsin monomolecular layer by the Langmuir-Blodgett film deposi... more We report herein the formation of pepsin monomolecular layer by the Langmuir-Blodgett film deposition technique. An effort was made to find an optimal subphase by adjusting the concentration of salt (KCl) and pH by monitoring the growth kinetics of pepsin for the formation of Langmuir monolayer by using as little as possible pepsin molecules to build up ultra thin film and to measure the extent of denaturation. Significant changes of area/molecule, compressibility, rigidity and unfolding of pepsin are observed at optimized subphase than pure water subphase. Observations at optimal subphase are explained in context of the modified DLVO theory and the site dissociation model. FTIR analysis of amide band together with the observed surface morphology of pepsin film in FE-SEM images indicate that at optimal subphase the pepsin molecules modify their structures by incrementing theˇ-structure, resulting into larger unfolding and inter-molecular aggregates.

Research paper thumbnail of Effect of Salt on the Formation of Alcohol-Dehydrogenease Monolayer: A Study by the Langmuir−Blodgett Technique

Journal of Physical Chemistry B, 2009

We report here the effect of salt (KCl) on the interfacial surface activity of yeast alcohol dehy... more We report here the effect of salt (KCl) on the interfacial surface activity of yeast alcohol dehydogenease (ADH) at air/water interface using the Langmuir-Blodgett technique. Effect of salt content in the water subphase on ADH structure has been studied. The change of area/molecule, compressibility, rigidity, and unfolding of ADH are insignificant up to 10 mM KCl concentration. The significant changes are observed above 0.1 M KCl concentrations. Observations are explained in the context of DLVO theory. FTIR study of amide band together with AFM imaging of ADH monolayer indicate that KCl perturbs the ADH monolayer by the increment of -structure resulting into larger unfolding and intermolecular aggregates at high salt concentration.

Research paper thumbnail of Interaction of glucose with hemoglobin: a study in aqueous solution and at the air-water interface using the Langmuir-Blodgett technique

Physical Chemistry Chemical Physics, 2011

Here, we report the glycosylation of human adult hemoglobin (Hb) studied in aqueous solution and ... more Here, we report the glycosylation of human adult hemoglobin (Hb) studied in aqueous solution and at the air-water interface by the Langmuir-Blodgett (LB) technique. Pressure-area (π-A) and pressure-time (π-t) measurements show that the concentration of glucose (GLC) and interaction time have an effect on Hb molecular area as well as on surface activity. Solution studies by UV-vis absorption and emission spectroscopy show that the GLC can alter the local conformation of Hb to some extent at the tryptophan and heme residues. CD spectroscopic studies in solution indicate that the α-helix content increases in the presence of GLC at the secondary structure level, which may be the cause of an increased adsorption rate of Hb. Also, secondary structure calculation using FTIR technique in the LB film follows the decrease in α-helix and increase in β-sheet structure as well as the formation of intermolecular aggregates. AFM images of Hb in the LB film indicate the transition from globular to an ellipsoid-like structure of Hb in the presence of GLC. FTIR studies of the LB film support the AFM imaging and the analysis of π-t kinetics. The molecular docking study revealed that Val 1 and Lys 132 are the most favorable docked sites along with some other sites such as Hem 147, Trp 37, Asp 94, Tyr 145, Leu 91, His 143, Glu 43 etc. The overall study may predict the processes of interactions with the increased concentration of GLC on Hb as well as on other long lived proteins.

Research paper thumbnail of pH Induced Structural Modulation and Interfacial Activity of Hemoglobin at the Air/Water Interface

Journal of Physical Chemistry B, 2010

In this Article, we report the surface activity of the human globular blood protein, hemoglobin (... more In this Article, we report the surface activity of the human globular blood protein, hemoglobin (Hb), at the air/water interface. The Langmuir-Blodgett technique is used for monolayer characterization. The adsorption growth-kinetics study shows that the adsorption process at the air/water interface is involved with two mechanisms: one diffusion with adsorption and the other rearrangement with unfolding. The kinetics is found to be dependent on pH and protein concentration in the subphase. The CD and FTIR studies suggest larger intermolecular aggregate and -sheet formation in the film lifted from the air/acidic water subphase. In alkaline pH and in isoelectric pH (6.8), not much variation is observed. The FE-SEM images support this observation. The acidic pH induced such conformational changes, and aggregation is explained with the argument of R-helix to -sheet conversion as well as the competition between protonation and deprotonation of the aromaticamino acid residues at the air/water interface.

Research paper thumbnail of Influence of KCl on the interfacial activity and conformation of hemoglobin studied by Langmuir-Blodgett technique

Physical Chemistry Chemical Physics, 2010

We report here the influence of KCl on the interfacial surface activity and conformation of human... more We report here the influence of KCl on the interfacial surface activity and conformation of human adult hemoglobin (Hb) using Langmuir and Langmuir-Blodgett (LB) techniques. The studies were done in absence and in presence of KCl salt in the subphase. We have studied the surface pressure-area (π-A) isotherm and surface pressure-time (π-t) kinetics of Hb with the variation of KCl concentrations (C(KCl)). The π-t study shows that the surface activity as well as the magnitude of diffusion and rearrangement of Hb at air/water interface is a function of C(KCl). Conformational study was done by CD spectroscopy and by the FTIR technique. Both the studies show an increasing trend of the α-helix form of Hb in the presence of KCl which may be responsible for the increased surface activity of Hb. The free energy calculations show that the compression of the Hb monolayer is involved in the small free energy change (∼5-25 kcal mol(-1)) of Hb. The changes in area per molecule and free energy, as well as other results, indicate that the influence of KCl on the Hb monolayer is in line with modified DLVO theory of ion-protein interaction. FE-SEM study shows that the LB films in absence of KCl comprise higher aggregates, whereas in the presence of KCl (0.5 M) it comprises lower aggregates, indicating the structural change of Hb. KCl salt here enhances the α-helix from of Hb, promoting the folded conformation by perturbing the water structure. The overall results show that the intermolecular forces and the surface activity as well as the population of the α-helix of Hb can be tuned by KCl salt.

Research paper thumbnail of Hemoglobin−Silver Interaction and Bioconjugate Formation: A Spectroscopic Study

Journal of Physical Chemistry B, 2010

In this article, we report the results of the extent of interaction as well as the formation of a... more In this article, we report the results of the extent of interaction as well as the formation of a bioconjugate of human hemoglobin (Hb) with silver (Ag). The complexation process and conformational changes are characterized using different spectroscopic and microscopic techniques. The UV-vis study demonstrates the perturbation of the soret/heme band and generates conformational heterogeneity within the heme group in the presence of silver. A fluorescence study suggests that the Tryptophan (Trp) residues of Hb are in a more polar environment after conjugation. Initial fluorescence enhancement with addition of silver is due to metalenhanced fluorescence. Moreover, the fluorescence quenching after the formation of the Hb-Ag bioconjugate follows the modified Stern-Volmer (S-V) plot. The S-V plot along with the time-resolved fluorescence study indicates the presence of both static and dynamic types of quenching. In addition, the reduction potential values of the entities (Hb-heme, Ag + , and Trp) indicate the possible electron transfer. The secondary structure calculation from CD and FTIR spectra indicate R-helix to -sheet conversion, and unfolding of Hb is also responsible for the bioconjugate formation. In addition, FE-SEM, phase contrast inverted microscopy (PCIM) images demonstrate the formation of the silver-protein bioconjugate. The overall data show that there is a change in the secondary as well as the tertiary structure of Hb after conjugation with silver.

Research paper thumbnail of On the origin of iron-oxide nanoparticle formation using phospholipid membrane template

Colloids and Surfaces B-biointerfaces, 2010

In this report, we have studied the formation of iron-oxide nanoparticle at biologically relevant... more In this report, we have studied the formation of iron-oxide nanoparticle at biologically relevant phospholipids, DPPC Langmuir monolayer at air/water interface. Water subphase contains FeCl 3 . Adsorption and agglomeration of Fe 3+ ions at DPPC head group have being monitored by Langmuir and Langmuir Blodgett (LB) technique. Adsorption kinetics (-t) as well as the surface pressure area (-A) isotherms measurement demonstrate the incorporation of Fe 3+ ion at DPPC monolayer. The amount of incorporation of Fe 3+ to the DPPC monolayer is FeCl 3 concentration and time dependent. This reaction kinetics is well fitted by single exponential association equation. The composite monolayers transferred to different substrates are characterized by UV-vis absorption spectroscopy and electron microscopy (FE-SEM and HR-TEM). Study shows the formation of monodisperse Fe 3 O 4 nanoparticle having size ∼20 nm coated with DPPC mono or multilayer. The overall study indicates that the formation as well as assembly of iron-oxide nanoparticle in two dimensions is possible using lipid monolayer as a template.

Research paper thumbnail of Study of silver nanoparticle–hemoglobin interaction and composite formation

Colloids and Surfaces B-biointerfaces, 2011

Nanoscience is now an expanding field of research and finds potential application in biomedical a... more Nanoscience is now an expanding field of research and finds potential application in biomedical area, but it is limited due to lack of comprehensive knowledge of the interactions operating in nano-bio system. Here, we report the studies on the interaction and formation of nano-bio complex between silver nanoparticle (AgNP) and human blood protein hemoglobin (Hb). We have employed several spectroscopic (absorption, emission, Raman, FTIR, CD, etc.) and electron diffraction techniques (FE-SEM and HR-TEM) to characterize the Hb-AgNP complex system. Our results show the Hb-AgNP interaction is concentration and time dependent. The AgNP particle can attach/come closer to heme, tryptophan, and amide as well aromatic amine residues. As a result, the Hb undergoes conformational change and becomes unfolded through the increment of ␤-sheet structure. The AgNP-Hb can form charge-transfers (CT) complex where the Hb-heme along with the AgNP involved in the electron transfer mechanism and form Hb-AgNP assembled structure. The electron transfer mechanism has been found to be dependent on the size of silver particle. The overall study is important in understanding the nano-bio system and in predicting the avenues to design and synthesis of novel nano-biocomposite materials in material science and biomedical area.

Research paper thumbnail of Immobilization and the conformational study of phospholipid and phospholipid-protein vesicles

Materials Science and Engineering: C, 2009

The present work demonstrates the immobilization of phospholipids and phospholipids-protein vesic... more The present work demonstrates the immobilization of phospholipids and phospholipids-protein vesicles on solid substrate by simple drop-cast technique. We have also studied the structural and conformational transition of protein (OVA) molecules when they are loaded in immobilized vesicles of DPPC. High-resolution FE-SEM imaging is used to study the structural aspects of the immobilized vesicles of DPPC and OVA loaded DPPC. FTIR analyses of amide bands are being used to inspect the extent of the conformational transitions of β-sheet to α-helix of OVA in immobilized DPPC vesicles. Immobilized OVA-DPPC vesicles provide the structure of individual OVA molecule attached with DPPC, without aggregation amongst them.

Research paper thumbnail of Tailor made synthesis of amphiphilic azoaromatics via regioselective C–N bond fusion. Comparative studies of surface properties of the two positional isomers and cobalt complexes

Dalton Transactions, 2010

Tailor made synthesis of the isomeric azoaromatics, HL 1 -HL 4 [HL = (arylamino)phenylazopyridine... more Tailor made synthesis of the isomeric azoaromatics, HL 1 -HL 4 [HL = (arylamino)phenylazopyridine] containing a single hydrophobic tail (C n = C 10 and C 12 ) is described. The coordination induced C-N bond fusion synthetic protocol has been successfully used for the synthesis of the compounds, which are subsequently characterized using various spectroscopic techniques. The single crystal X-ray structure of compound HL 4 has revealed that the hydrophobic chain in it orients itself with all-trans conformation of alkyl groups. Studies of their surface properties clearly demonstrate that these behave as surfactants. Amphiphilic properties of the compounds are followed by the studies of compression isotherms and their surface morphologies are studied with the use of high resolution field emission scanning electron microscopy (FE-SEM) as well as atomic force microscopy (AFM). Distinct differences in surface properties in the two HL isomers are observed and disposition of the hydrophobic tail with respect to the head group is shown to play a significant role in the organization process of the molecules at the air-water interface. Transferred monolayers of the above two isomeric compounds show agglomerated nano-domain structures. This phenomenon has been explained considering hydrophobic tail-tail repulsive interaction within the adjacent molecules. Surface properties of the double tail complex, [Co(L 1 ) 2 ]ClO 4 (1) along with that of the single tail complex, [Co(L 1 )(L 5 )]ClO 4 (3) are also reported. Amphiphilic behavior of the above azoaromatics are distinctly different than those in their metal free state. Notably, the double tail complex (1) favors bi-layer formation even at low surface pressure region (~10 mN m -1 ). The single tail cobalt complex (3), on the other hand, forms a monolayer at high surface pressure region leading finally to the collapse at a very high pressure~60 mN m -1 .

Research paper thumbnail of The formation of pepsin monomolecular layer by the Langmuir–Blodgett film deposition technique

Colloids and Surfaces B-biointerfaces, 2009

We report herein the formation of pepsin monomolecular layer by the Langmuir-Blodgett film deposi... more We report herein the formation of pepsin monomolecular layer by the Langmuir-Blodgett film deposition technique. An effort was made to find an optimal subphase by adjusting the concentration of salt (KCl) and pH by monitoring the growth kinetics of pepsin for the formation of Langmuir monolayer by using as little as possible pepsin molecules to build up ultra thin film and to measure the extent of denaturation. Significant changes of area/molecule, compressibility, rigidity and unfolding of pepsin are observed at optimized subphase than pure water subphase. Observations at optimal subphase are explained in context of the modified DLVO theory and the site dissociation model. FTIR analysis of amide band together with the observed surface morphology of pepsin film in FE-SEM images indicate that at optimal subphase the pepsin molecules modify their structures by incrementing theˇ-structure, resulting into larger unfolding and inter-molecular aggregates.

Research paper thumbnail of Effect of Salt on the Formation of Alcohol-Dehydrogenease Monolayer: A Study by the Langmuir−Blodgett Technique

Journal of Physical Chemistry B, 2009

We report here the effect of salt (KCl) on the interfacial surface activity of yeast alcohol dehy... more We report here the effect of salt (KCl) on the interfacial surface activity of yeast alcohol dehydogenease (ADH) at air/water interface using the Langmuir-Blodgett technique. Effect of salt content in the water subphase on ADH structure has been studied. The change of area/molecule, compressibility, rigidity, and unfolding of ADH are insignificant up to 10 mM KCl concentration. The significant changes are observed above 0.1 M KCl concentrations. Observations are explained in the context of DLVO theory. FTIR study of amide band together with AFM imaging of ADH monolayer indicate that KCl perturbs the ADH monolayer by the increment of -structure resulting into larger unfolding and intermolecular aggregates at high salt concentration.

Research paper thumbnail of Interaction of glucose with hemoglobin: a study in aqueous solution and at the air-water interface using the Langmuir-Blodgett technique

Physical Chemistry Chemical Physics, 2011

Here, we report the glycosylation of human adult hemoglobin (Hb) studied in aqueous solution and ... more Here, we report the glycosylation of human adult hemoglobin (Hb) studied in aqueous solution and at the air-water interface by the Langmuir-Blodgett (LB) technique. Pressure-area (π-A) and pressure-time (π-t) measurements show that the concentration of glucose (GLC) and interaction time have an effect on Hb molecular area as well as on surface activity. Solution studies by UV-vis absorption and emission spectroscopy show that the GLC can alter the local conformation of Hb to some extent at the tryptophan and heme residues. CD spectroscopic studies in solution indicate that the α-helix content increases in the presence of GLC at the secondary structure level, which may be the cause of an increased adsorption rate of Hb. Also, secondary structure calculation using FTIR technique in the LB film follows the decrease in α-helix and increase in β-sheet structure as well as the formation of intermolecular aggregates. AFM images of Hb in the LB film indicate the transition from globular to an ellipsoid-like structure of Hb in the presence of GLC. FTIR studies of the LB film support the AFM imaging and the analysis of π-t kinetics. The molecular docking study revealed that Val 1 and Lys 132 are the most favorable docked sites along with some other sites such as Hem 147, Trp 37, Asp 94, Tyr 145, Leu 91, His 143, Glu 43 etc. The overall study may predict the processes of interactions with the increased concentration of GLC on Hb as well as on other long lived proteins.

Research paper thumbnail of pH Induced Structural Modulation and Interfacial Activity of Hemoglobin at the Air/Water Interface

Journal of Physical Chemistry B, 2010

In this Article, we report the surface activity of the human globular blood protein, hemoglobin (... more In this Article, we report the surface activity of the human globular blood protein, hemoglobin (Hb), at the air/water interface. The Langmuir-Blodgett technique is used for monolayer characterization. The adsorption growth-kinetics study shows that the adsorption process at the air/water interface is involved with two mechanisms: one diffusion with adsorption and the other rearrangement with unfolding. The kinetics is found to be dependent on pH and protein concentration in the subphase. The CD and FTIR studies suggest larger intermolecular aggregate and -sheet formation in the film lifted from the air/acidic water subphase. In alkaline pH and in isoelectric pH (6.8), not much variation is observed. The FE-SEM images support this observation. The acidic pH induced such conformational changes, and aggregation is explained with the argument of R-helix to -sheet conversion as well as the competition between protonation and deprotonation of the aromaticamino acid residues at the air/water interface.

Research paper thumbnail of Influence of KCl on the interfacial activity and conformation of hemoglobin studied by Langmuir-Blodgett technique

Physical Chemistry Chemical Physics, 2010

We report here the influence of KCl on the interfacial surface activity and conformation of human... more We report here the influence of KCl on the interfacial surface activity and conformation of human adult hemoglobin (Hb) using Langmuir and Langmuir-Blodgett (LB) techniques. The studies were done in absence and in presence of KCl salt in the subphase. We have studied the surface pressure-area (π-A) isotherm and surface pressure-time (π-t) kinetics of Hb with the variation of KCl concentrations (C(KCl)). The π-t study shows that the surface activity as well as the magnitude of diffusion and rearrangement of Hb at air/water interface is a function of C(KCl). Conformational study was done by CD spectroscopy and by the FTIR technique. Both the studies show an increasing trend of the α-helix form of Hb in the presence of KCl which may be responsible for the increased surface activity of Hb. The free energy calculations show that the compression of the Hb monolayer is involved in the small free energy change (∼5-25 kcal mol(-1)) of Hb. The changes in area per molecule and free energy, as well as other results, indicate that the influence of KCl on the Hb monolayer is in line with modified DLVO theory of ion-protein interaction. FE-SEM study shows that the LB films in absence of KCl comprise higher aggregates, whereas in the presence of KCl (0.5 M) it comprises lower aggregates, indicating the structural change of Hb. KCl salt here enhances the α-helix from of Hb, promoting the folded conformation by perturbing the water structure. The overall results show that the intermolecular forces and the surface activity as well as the population of the α-helix of Hb can be tuned by KCl salt.

Research paper thumbnail of Hemoglobin−Silver Interaction and Bioconjugate Formation: A Spectroscopic Study

Journal of Physical Chemistry B, 2010

In this article, we report the results of the extent of interaction as well as the formation of a... more In this article, we report the results of the extent of interaction as well as the formation of a bioconjugate of human hemoglobin (Hb) with silver (Ag). The complexation process and conformational changes are characterized using different spectroscopic and microscopic techniques. The UV-vis study demonstrates the perturbation of the soret/heme band and generates conformational heterogeneity within the heme group in the presence of silver. A fluorescence study suggests that the Tryptophan (Trp) residues of Hb are in a more polar environment after conjugation. Initial fluorescence enhancement with addition of silver is due to metalenhanced fluorescence. Moreover, the fluorescence quenching after the formation of the Hb-Ag bioconjugate follows the modified Stern-Volmer (S-V) plot. The S-V plot along with the time-resolved fluorescence study indicates the presence of both static and dynamic types of quenching. In addition, the reduction potential values of the entities (Hb-heme, Ag + , and Trp) indicate the possible electron transfer. The secondary structure calculation from CD and FTIR spectra indicate R-helix to -sheet conversion, and unfolding of Hb is also responsible for the bioconjugate formation. In addition, FE-SEM, phase contrast inverted microscopy (PCIM) images demonstrate the formation of the silver-protein bioconjugate. The overall data show that there is a change in the secondary as well as the tertiary structure of Hb after conjugation with silver.

Research paper thumbnail of On the origin of iron-oxide nanoparticle formation using phospholipid membrane template

Colloids and Surfaces B-biointerfaces, 2010

In this report, we have studied the formation of iron-oxide nanoparticle at biologically relevant... more In this report, we have studied the formation of iron-oxide nanoparticle at biologically relevant phospholipids, DPPC Langmuir monolayer at air/water interface. Water subphase contains FeCl 3 . Adsorption and agglomeration of Fe 3+ ions at DPPC head group have being monitored by Langmuir and Langmuir Blodgett (LB) technique. Adsorption kinetics (-t) as well as the surface pressure area (-A) isotherms measurement demonstrate the incorporation of Fe 3+ ion at DPPC monolayer. The amount of incorporation of Fe 3+ to the DPPC monolayer is FeCl 3 concentration and time dependent. This reaction kinetics is well fitted by single exponential association equation. The composite monolayers transferred to different substrates are characterized by UV-vis absorption spectroscopy and electron microscopy (FE-SEM and HR-TEM). Study shows the formation of monodisperse Fe 3 O 4 nanoparticle having size ∼20 nm coated with DPPC mono or multilayer. The overall study indicates that the formation as well as assembly of iron-oxide nanoparticle in two dimensions is possible using lipid monolayer as a template.

Research paper thumbnail of Study of silver nanoparticle–hemoglobin interaction and composite formation

Colloids and Surfaces B-biointerfaces, 2011

Nanoscience is now an expanding field of research and finds potential application in biomedical a... more Nanoscience is now an expanding field of research and finds potential application in biomedical area, but it is limited due to lack of comprehensive knowledge of the interactions operating in nano-bio system. Here, we report the studies on the interaction and formation of nano-bio complex between silver nanoparticle (AgNP) and human blood protein hemoglobin (Hb). We have employed several spectroscopic (absorption, emission, Raman, FTIR, CD, etc.) and electron diffraction techniques (FE-SEM and HR-TEM) to characterize the Hb-AgNP complex system. Our results show the Hb-AgNP interaction is concentration and time dependent. The AgNP particle can attach/come closer to heme, tryptophan, and amide as well aromatic amine residues. As a result, the Hb undergoes conformational change and becomes unfolded through the increment of ␤-sheet structure. The AgNP-Hb can form charge-transfers (CT) complex where the Hb-heme along with the AgNP involved in the electron transfer mechanism and form Hb-AgNP assembled structure. The electron transfer mechanism has been found to be dependent on the size of silver particle. The overall study is important in understanding the nano-bio system and in predicting the avenues to design and synthesis of novel nano-biocomposite materials in material science and biomedical area.

Research paper thumbnail of Immobilization and the conformational study of phospholipid and phospholipid-protein vesicles

Materials Science and Engineering: C, 2009

The present work demonstrates the immobilization of phospholipids and phospholipids-protein vesic... more The present work demonstrates the immobilization of phospholipids and phospholipids-protein vesicles on solid substrate by simple drop-cast technique. We have also studied the structural and conformational transition of protein (OVA) molecules when they are loaded in immobilized vesicles of DPPC. High-resolution FE-SEM imaging is used to study the structural aspects of the immobilized vesicles of DPPC and OVA loaded DPPC. FTIR analyses of amide bands are being used to inspect the extent of the conformational transitions of β-sheet to α-helix of OVA in immobilized DPPC vesicles. Immobilized OVA-DPPC vesicles provide the structure of individual OVA molecule attached with DPPC, without aggregation amongst them.

Research paper thumbnail of Tailor made synthesis of amphiphilic azoaromatics via regioselective C–N bond fusion. Comparative studies of surface properties of the two positional isomers and cobalt complexes

Dalton Transactions, 2010

Tailor made synthesis of the isomeric azoaromatics, HL 1 -HL 4 [HL = (arylamino)phenylazopyridine... more Tailor made synthesis of the isomeric azoaromatics, HL 1 -HL 4 [HL = (arylamino)phenylazopyridine] containing a single hydrophobic tail (C n = C 10 and C 12 ) is described. The coordination induced C-N bond fusion synthetic protocol has been successfully used for the synthesis of the compounds, which are subsequently characterized using various spectroscopic techniques. The single crystal X-ray structure of compound HL 4 has revealed that the hydrophobic chain in it orients itself with all-trans conformation of alkyl groups. Studies of their surface properties clearly demonstrate that these behave as surfactants. Amphiphilic properties of the compounds are followed by the studies of compression isotherms and their surface morphologies are studied with the use of high resolution field emission scanning electron microscopy (FE-SEM) as well as atomic force microscopy (AFM). Distinct differences in surface properties in the two HL isomers are observed and disposition of the hydrophobic tail with respect to the head group is shown to play a significant role in the organization process of the molecules at the air-water interface. Transferred monolayers of the above two isomeric compounds show agglomerated nano-domain structures. This phenomenon has been explained considering hydrophobic tail-tail repulsive interaction within the adjacent molecules. Surface properties of the double tail complex, [Co(L 1 ) 2 ]ClO 4 (1) along with that of the single tail complex, [Co(L 1 )(L 5 )]ClO 4 (3) are also reported. Amphiphilic behavior of the above azoaromatics are distinctly different than those in their metal free state. Notably, the double tail complex (1) favors bi-layer formation even at low surface pressure region (~10 mN m -1 ). The single tail cobalt complex (3), on the other hand, forms a monolayer at high surface pressure region leading finally to the collapse at a very high pressure~60 mN m -1 .