The peak location of the localized surface plasmon resonance (LSPR) of noble metal nanoparticles is highly dependent upon the refractive index of the nanoparticles' surrounding environment. In this study, new phenomena are revealed by exploring the influence of interacting molecular resonances and nanoparticle resonances. The LSPR peak shift and line shape induced by a resonant molecule vary with wavelength. In most instances, the oscillatory dependence of the peak shift on wavelength tracks with the wavelength dependence of the real part of the refractive index, as determined by a Kramers−Kronig transformation of the molecular resonance absorption spectrum. A quantitative assessment of this shift based on discrete dipole approximation calculations shows that the Kramers−Kronig index must be scaled in order to match experiment.

Localized Surface Plasmon Resonance Spectroscopy near Molecular Resonances

Chemical sensing–whether for human health assessment, environmental quality monitoring, or myriad other purposes–generally entails: a) recognition and binding, adsorption, or other interaction with the molecule or ion to be sensed, and b) transduction of the recognition/binding event into an externally observable signal.[1] Coordination-based supramolecular chemistry, with its ability to generate an enormous Scheme 4. Boronic ester annulation/Diels±Alder cycloaddition sequence performed on the high capacity bead-linker reagent used in a one-bead, one-stock solution platform for chemical genetics. a) 1-propynylmagnesium bromide, THF, 0 C RT; b) 4 (10 equiv), 5 (15 mol%), CH2Cl2, 40 C; c) N-benzylmeleimide (8 equiv), PhMe, 80 C; d) H2O2, NaOH, THF; e) HF ¥ pyr/pyr, THF. pyr pyridine.

Microporous supramolecular coordination compounds as chemosensory photonic lattices.

Interest in electrochromic π -conjugated polymers (ECPs) has recently increased considerably for their tunability of colors, low cost of preparation, and low-voltage operation. [ 1–11 ] Among the ECPs, polymers from heterocyclic monomers containing pyrrole, [ 12 ] thiophene, [ 13 ] and selenophene [ 14–16 ] derivatives have been applied to electrochromic devices for simple fi lm processing and high electrochromic contrast. In particular, recent advances in the synthesis of poly(3,4-alkylenedioxythiophene)s (PXDOTs) and their derivatives have offered new opportunities for low energy consumption and electrochemically stable transmissive/absorptive electrochromic devices (ECDs) with fast switching times and full color. [ 17–21 ]

Solution Processable and Patternable Poly(3,4‐alkylenedioxythiophene)s for Large‐Area Electrochromic Films

This paper gives an overview of the use of poly(ferrocenylsilane)s in the surface patterningof silicon substrates. Due to the presence of iron and silicon in their main chain, poly(ferrocenylsilane)sshow a very high resistance to reactive ion etching, allowing one to transfer polymer patternsdirectly onto the substrate. Methods for introducing etch-resistant polymer patterns on substratesurfaces include soft lithography approaches such as microcontact printing, directed dewetting, andcapillary force lithography. Next to top-down methods, self-assembly strategies are discussed. Phaseseparation in thin films of asymmetric organic–organometallic block copolymers leads to theformation of nanoperiodic organometallic patterns. The use of such thin films as nanolithographictemplates is demonstrated. Surface patterning can also be realized using electrostatic self-assemblyof organometallic polyions. Layer-by-layer deposition of poly(ferrocenylsilane) polyanions and polycationson chemically patterned substrates allows one to guide the growth of multilayer thin films and toproduce patterned organometallic coatings.

Surface Nano- and Microstructuring with Organometallic Polymers

Poly(3-hexylthiophene) (P3HT) films were patterned by a soft lithography technique using a nanopatterned polydimethylsiloxane (PDMS) mold to generate one-dimensional (1D) grating and two-dimensional (2D) crossed line pillar patterns. The redox currents (i(p)) were significantly increased due to the facilitated diffusion of ClO4(-) counterions associated with redox processes at the P3HT electrode as analyzing cyclic voltammetry (CV) was performed at different scan rates (ν). It was found that the diffusion coefficient (D(f), cm(2) s(-1)) for ion diffusion in the patterned electrode was much larger than that of the pristine P3HT electrode. Furthermore, the value of D(f) in the 2D electrode was three times higher than that in a pristine film. As a result of such facilitated charge transport, the electrochromic (EC) properties of the patterned P3HT electrode were greatly enhanced and dependent on the dimension of the pattern. Thus, the electrochromic efficiency (E(e)), including the coloration (E(c)) and bleaching efficiencies (E(b)), was higher as the dimension of the pattern was increased; E(e) was maximized in the 2D patterned P3HT film. In a patterned cell, electrochromic diffraction was reversibly observed with a switching efficiency (R(DE)) of 2 and 2.5 for the 1D and 2D patterned cells, respectively.

Electrochromic diffraction from nanopatterned poly(3-hexylthiophene).

This manuscript presents an overview of work directed toward the creation of arbitrary micron-scale patterns of electroactive polymer films by the application of photolithography. A brief overview of work by other groups in the field is followed by a detailed description of work from our own labs which resulted in the development of methods to pattern a variety of different electroactive materials, including Ru− and Os−polypyridine complexes, viologen-based polymers, and a low-potential polythiophene. The discussion provides detail on the photolithographic methodology. In addition, the spatially-patterned films are characterized by using optical and scanning electron microscopy. The voltammetric and spectroelectrochemical properties of several of the lithographically-patterned films are also presented. Finally, photolithography is applied to fabricate electrochromic optical diffraction gratings. The diffraction efficiency of these electroactive gratings can be modulated by an electrochemical stimulus. The...

Carla S. P. Cavalaheiro

Papers

Photolithographically-Patterned Electroactive Films and Electrochemically Modulated Diffraction Gratings