Layer-by-Layer Growth of Acentric Multilayers of Zr and Azobenzene Bis(phosphonate):  Structure, Composition, and Second-Order Nonlinear Optical Properties

Abstract

This paper describes the use of layer-by-layer growth of metal−bis(phosphonate) multilayers to produce acentric thin films with second-order nonlinear optical properties. To incorporate such properties, organic “chromophore” molecules containing conjugated π systems situated between electron donor and electron acceptor groups are oriented uniformly within the film such that the bulk structure is noncentrosymmetric. This is accomplished using chromophoric α,ω-bis(phosphonate) molecules that have one terminal phosphonate group “protected” in ester form, whereas the other is a free phosphonic acid that will bind to a metal-primed silicon or glass surface. After deposition of the acid moiety onto metal-primed silicon, the ester groups are hydrolyzed to enable deposition of additional metal and chromophore layers. We report here the results of this approach using the chromophore bis(1-ethyl)3-{N-methyl[(4-[(4-phenylphosphonic acid)azo]phenyl)amino]decyl}phosphonate, or azobenzene molecule I. Results from multilayer studies and monolayer and solution studies are discussed, with emphasis on results from UV−vis spectroscopy, grazing angle X-ray diffraction, and second harmonic generation.

Metal Phosphonates Applied to Biotechnologies: A Novel Approach to Oligonucleotide Microarrays

“…[41] Our groups have used this chemistry to form monolayer films of organophosphonates with organic groups ranging from simple alkanes [41] to azobenzene, [45] tetrathiafulvalene, [55] phenoxy and biphenoxy groups, [43] and porphyrins. [46] The zirconium phosphonate-modified surfaces can be prepared in different ways, but often involve binding of Zr 4 + ions to phosphorylated groups deposited onto silica [50,51,54,[56][57][58][59][60][61] or gold ( Figure 6). [52,54,56,57,62] Our experience is that exceptionally smooth and uniform films can be gener- Chem.…”

Electric-field-induced layer-by-layer fabrication of inorganic–organic hybrid second-order nonlinear optical films

“…[1][2][3][4][5]. Organic films with noncentrosymmetric structures for SONLO properties have been prepared using a variety of methods, including electric field poling [6][7][8], LangmuirBlodgett (LB) films [9][10][11][12], covalent self-assembly [13][14][15][16], and so on. The poor temporal or mechanical stability of the poled polymer systems and LB films restrict their potential applications [17,18].…”

Nonlinear optical, poly(amide-imide)–clay nanocomposites comprising an azobenzene moiety synthesised via sequential self-repetitive reaction

“…Smectite clay minerals, such as montmorillonite (MMT), having appropriate functional molecules in between the silicate layers (which is called intercalation) are supposed to exhibit a wide range of novel characteristics such as ion conductivity and unusual electric and NLO properties [22][23][24][25][26]. In our previous investigation [25], the polyimide/MMT materials show much better long-term NLO stability at elevated temperatures than the pristine polyimide.…”