The monomer-aggregate equilibrium of four phenothiazine (PN) dyes, containing thionine (TH), methylene blue (MB), new methylene blue (NMB), and 1,9-dimethylmethylene blue (DMB), in the tungsten(VI) oxide (WO(3)) nanocolloid solution has been investigated by means of UV-vis spectroscopy. Addition of PN dye into the WO(3) nanocolloid solution brought about significant changes in the absorption spectrum, suggesting the formation of H-type (face-to-face fashion) trimer on the WO(3) nanocolloid surface. The adsorptivity of PN dyes onto the WO(3) nanocolloid surface was diminished by the raising the ionic strength, indicating the evidence of the electrostatic interaction between cationic PN dye and negatively charged WO(3) nanocolloids. The detail analysis of each spectral data provided insight into the effect of molecular structure of PN dyes on the adsorption and aggregation behaviors on the WO(3) nanocolloid surface. Moreover, in situ measurement of PN dye aggregation using the centrifugal liquid membrane (CLM) technique revealed that the aggregation of PN dyes on the WO(3) nanocolloid surface proceeded in a two-step three-stage (monomer --> dimer --> trimer) formation. The aggregation mechanism of PN dyes on the WO(3) nanocolloid surface was discussed on the basis of Kasha's exciton theory.

The centrifugal liquid membrane (CLM) cell has been utilized for chiroptical studies of liquid-liquid interfaces with a conventional circular dichroism (CD) spectropolarimeter. These studies required the characterization of optical properties of the rotating cylindrical CLM glass cell, which was used under the high speed rotation. In the present study, we have measured the circular and linear dichroism (CD and LD) spectra and the circular and linear birefringence (CB and LB) spectra of the CLM cell itself as well as those of porphyrine aggregates formed at the liquid-liquid interface in the CLM cell, applying Mueller matrix measurement method. From the results, it was confirmed that the CLM-CD spectra of the interfacial porphyrin aggregates observed by a conventional CD spectropolarimeter should be correct irrespective of LD and LB signals in the CLM cell.

Previous direct observations of the J aggregates of diprotonated 5,10,15,20-tetraphenyl-21H,23H-porphine (H4TPP(2+)) formed at the dodecane-water interface in a centrifugal liquid membrane (CLM) cell using conventional CD spectroscopy have shown the existence of circular dichroic signals with a bisignated shape whose sign depends on the rotation direction of the cell. Herein we demonstrate that the determination of the optical Mueller matrix with a two-photoelastic modulator generalized ellipsometer (2-MGE), working in transmission mode, along with the assumption of a two superimposed twin Mueller matrices model (two opposite interfaces in the cylindrical rotation cell) allows us to infer the CD spectra due to overlapping linear polarizations from J aggregates at the front and back liquid-liquid interfaces in the rotating cell. The rotation direction dependence of the CD spectra was thoroughly interpreted by the present model considering the sign and the magnitude of the orientation angle between the front and back J aggregates. The present analysis should help us to understand the optical chirality due to the structural changes in supramolecular and macromolecular systems under flow shear forces as well as changes in birefringence.

A microscope device to measure the circular dichroism (CD) spectra of a specified microscopic region of chiral samples was constructed by combining of a couple of objective lenses and a CCD camera, which was installed in a sample chamber of a commercially available CD spectropolarimeter. By using this apparatus, high quality micro-CD spectra in the 60 × 60 μm region of samples could be measured. Micro-CD spectra of thin film of chiral DNA samples on glass and a natural kidney bean leaf were measured, and the potential of the micro-CD apparatus was successfully demonstrated.

In the methylene blue (MB)/phenylalanine (Phe)/tungsten(VI) oxide (WO 3 ) colloid ternary aqueous solution, the MB Haggregates, which could recognize the chirality of D-and L-10 Phe, were formed and investigated by means of UV-Vis absorption and CD spectroscopy. These results demonstrate a chirality transfer and amplification from only the preadsorbed Phe molecules to MB aggregates formed on the WO 3 colloid surface via non-covalent interactions. 15Amino acids are important bioactive substances, they are widely used in the food, chemical and pharmaceutical industries. [1,2] Enantioselective recognition of amino acids is an important methodology for providing a better understanding of the origin of homochirality and leading to better development of biochemical 20 and pharmaceutical chiral devices. [3][4][5][6] Great efforts have been made to recognize amino acid enantiomers, but designing an efficient method to recognize amino acids is still a challenging task. [7] There are great interests concerning the transformation of chiral information from a chiral template to achiral molecules and 25 supramolecular systems.[8] By forming intrinsically chiral assemblies, or by aggregating on a chiral template, the symmetric achiral molecules could also present supramolecular chirality. Construction of a chiral molecular assembly is very important in supramolecular chiral recognition. [9][10][11] The driving force for the 30 formation of chiral supermolecules is generally constructed on the non-covalent interactions, such as van der Waals interactions, hydrogen bonds, π-π stacking, electrostatic interaction and hydrophobic interactions. [12][13][14] Phenothiazine derivatives such as methylene blue (MB) play 35 important roles in spectroscopic studies for their novel and tunable spectroscopic, photophysical and photochemical properties. [15,16] Their unique planar as well as rigid molecular geometry and aromatic electronic feature delocalized over the molecular frame enable them to be well investigated in the field 40 of constructing supramolecular assemblies by non-covalent interactions. In our previously reported work, [17] we found that the cationic MB dyes could form ideal H-type (face-to-face fashion) trimer on the negative charged tungsten(IV) oxide (WO 3 ) nanocolloid surface via the supramolecular self-assembly 45 process in the aqueous solution.Inspired by this finding, we have introduced the concept of "chirality" into the MB/WO 3 binary system by adding phenylalanine (Phe) which is one of the amino acids that are joined together to form proteins. Once the supramolecular 50 chirality in the MB/Phe/WO 3 ternary system has been achieved, one can expect that the system would show more important and more interesting optical active architectures from the viewpoints of chiral recognition mechanism and organic/inorganic hybrid material. Herein, we describe an investigation of supramolecular

Circular dichroism (CD) was observed from the superposed porphyrin deposited glass plates, which were prepared by the vapor deposition of achiral porphyrin molecules and oriented to one direction by rubbing parallel to the surface of plate. The CD spectra depended on the twisted angle between the plates and the number of plates superposed. The observed CD spectra agreed with the simulated ones by the Mueller matrices superposition calculation using the observed linear dichroism spectra and linear birefringence spectra of each plate.

The J-aggregate of diprotonated tetraphenylporphyrin (H(4)TPP(2+)) formed at the dodecane-water interface showed circular dichroism spectra corresponding to the chirality of 2-alkyl alcohols, longer than 2-butanol, added to the dodecane phase. The phenomenon suggested the preferential interaction between the nano-sized J-aggregates and the chiral alcohols at the interface, and provided a potential use of the J-nanoaggregate as a chiral recognition probe.

The apparent circular dichroism (CD) and the linear dichroism (LD) spectra of the aggregates of achiral zinc(II)-5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP), formed at the toluene/water interface in a centrifugal liquid membrane (CLM) cell, were investigated by comparison with the microscopic CD and LD spectra of a single interfacial aggregate of ZnTPyP about 100 mum in length, measured by a microscope-spectropolarimeter. The interfacial ZnTPyP aggregate showed two types of flat trapezoidal shapes, one had a seedlike core at an edge (type I) and another a needlelike core at an edge (type II). The microscopic CD and LD spectra were observed by varying the angle between the parallel axis of the trapezoidal aggregate and the perpendicular axis of a polarized light for LD. The plot of the CD intensity against the LD intensity for a single aggregate, observed at a given wavelength, showed a rotated elliptical shape with a long axis through the origin, when the orientation angle was changed. From these results, it was concluded that the apparent CD spectra observed by the CLM-CD method were mainly due to the large linear dichroism of the aggregate. Both type I and type II structures showed two transition dipole moments, parallel and perpendicular to the long axis of the structure, but suggesting a more developed J-aggregate in type II structure. AFM measurements showed that the interfacial ZnTPyP aggregate had a multilayer structure, in which the unit monolayer thickness was 1.58 +/- 0.23 nm. Finally, the orientation angle of the interfacial aggregate in the CLM cell was estimated as 41 degrees -44 degrees to the rotating axis of the cell.