A novel highly ordered layered superlattice multibilayer film is prepared by casting the chloroform solutions of ionic complex between a polyoxotungstoeuropate anion EuW10O369−
(EuW10) and a hexadecyltrimethylammonium cation (C16TA) on hydrophilic substrates. A variety of techniques, including FT-IR and UV–vis spectroscopies, differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to characterize the structure of the composite film. The lamellae consist of alternating layers of polyoxotungstoeuropate and bimolecular layers of surfactant, with the surfactant alkyl chains tilted 30.8° to the lamellar surface and noninterdigititated. The photoluminescent behavior of the film at room temperature has also been investigated by fluorescence spectroscopy to show the characteristic Eu3+ emission pattern of 5D0
→
7Fj. The fluorescence spectra and fluorescence lifetime of the composite film are quite different from those found for EuW10 solid powder and EuW10 dilute aqueous solution.

Highly ordered photoluminescent self-assembled films based on polyoxotungstoeuropate complex Na9[EuW10O36]

The laterally nonsymmetric aza cryptand synthesized by condensing tris(2-aminoethyl)amine (tren) with tris{[2-(3-(oxomethyl)phenyl)oxy]ethyl}amine readily forms mononuclear inclusion complexes with both transition and main-group metal ions. In these complexes, the metal ion occupies the tren-end of the cavity making bonds with the three secondary amino and the bridgehead N atoms. When a strong π-acceptor group such as 2,4-dinitrobenzene is attached to one of the secondary amines, the binding property of the cryptand changes drastically. When perchlorate or tetrafluoroborate salts of Ni(II), Cu(II), Zn(II), or Cd(II) are used, the metal ion enters the cavity which can be monitored by the hypsochromic shift of the intramolecular charge-transfer transition from the donor amino N atom to the acceptor dinitrobenzene. However, in the presence of coordinating ions such as Cl-, N3-, and SCN-, the metal ion comes out of the cavity and binds the cryptand outside the cavity at a site away from the dinitrobenzene moi...

Metal binding characteristics of a laterally nonsymmetric Aza cryptand upon functionalization with a π-acceptor group

The complexation of monoalkyl derivatives of ethylenediamine, CnH2n+1NHCH2CH2NH2 (n = 8, 12, 14, 16, and 18), to CuX2 (X- = Cl- or ClO4-) in dilute aqueous dispersions can form stable synthetic bilayer membranes. The aggregate structure and properties of the bilayer membranes have been investigated thoroughly by small-angle X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, electronic reflectance spectroscopy, and differential scanning calorimetry (DSC). The results confirm a strong influence of the counterions on the organized structure of Cu2+-coordinated bilayer membranes. When X- = Cl-, the Cu2+-coordinated headgroups adopt a trans configuration, which gives a compressed tetrahedral CuN4 environment, and the two tails in the complex take an approximately diagonal position with tilted tail-to-tail packing fashion in bilayer assemblages. When X- = ClO4-, a cis configuration is adopted in the square plane of the Cu2+-coordinated headgroups, and the two tails are located at the same...

Effect of Counterions on the Organized Structure of Cu2+-Coordinated Bilayer Membranes Formed by Monoalkyl Derivatives of Ethylenediamine

On the role of an unconventional rigid rodlike cationic surfactant on the styrene emulsion polymerization. Kinetics, particle size and particle size distribution

Three derivatives of tris(bipyridyl)–ruthenium(II) complexes with different alkyl-chain lengths (nC18H37 (1), nC14H29 (2) and nC10H21 (3)) were synthesised. All these complexes behaved as an amphiphile and their surface properties were studied at the air–water interface by measuring surface pressure–area (Π–A) isotherms. The surface morphology of the resulting films at the air–water interface was also studied by using Brewster angle microscopy. Mean molecular areas of these complexes were measured from the Π–A isotherms, which were approximately 200 A2, thereby indicating a parallel arrangement of the Ru–bipyridyl moiety of the complexes. Mono- and multilayer Langmuir–Blodgett (LB) films were formed on different solid surfaces with transfer ratios close to one. Similarities in the absorption and fluorescence spectra of these amphiphiles in solution as well as in LB films deposited on a quartz surface confirmed the successful transfer of these films onto the substrates. The latter provided information about the arrangements of metallosurfactant molecules within the LB films. The two-dimensional concentrations of these films were calculated from the Lambert–Beer law as well as from the Π–A isotherm, which confirmed regular and reproducible transfer of the complex monolayers from the air–water interface onto the quartz surface. The surface morphology of these films on various substrates was characterised by atomic force microscopy. Furthermore, by oxidising the monolayer of complex 3, a one-input sequential logic gate was constructed.

Interfacial and Film-Formation Behaviour of Photoactive RuII–Bipyridyl-Based Metallosurfactants and a Rare Example of a Monolayer-Based Logic-Gate Approach

A cryptand incorporating three secondary amino groups has been derivatized by reacting with acid chlorides of different alkyl chain lengths (between C4 and C15) to get a new generation of six crypt...

Synthesis and characterization of a new generation of cryptand-based triple-tailed amphiphiles : Spontaneous formation of vesicles and X-ray crystallographic studies

Syntheses of a number of cryptands having heteroditopic as well as heterotritopic receptor sites have been achieved using alkali metal ions as templates. Some of the cryptands can be synthesized on a multi-gram scale without using any templating metal ions at low temperature (278 K). Each of these cryptands readily forms inclusion complexes with transition metal ions. These cryptands exhibit interesting properties and can further accomodate small anions inside the cavity. Further, upon suitable derivatization, some of the cryptands can behave as amphiphiles and form Langmuir-Blodgett films very readily. When derivatized with 9-methylanthracene, some of the cryptands show interesting fluorescence properties and can be of use as molecular photonic devices.

Sayam Sengupta

Papers

Synthesis and characterization of a new generation of cryptand-based triple-tailed amphiphiles : Spontaneous formation of vesicles and X-ray crystallographic studies

Synthesis and uses of macrobicyclic cryptands: from complexation of transition metal ions to molecular devices