Organic thin films, molecular self-assembly

The highly oriented molecules in thin organic films such as Langmuir-Blodgett (LB) films and self-assembled monolayers (SAM) [1] are essential for some molecular functions. Non linear optical and opto-electronic properties are two of the most important and interesting functions of these molecular assemblies. In the past more than thirteen years, simulation of the primary process of photosynthesis using such molecular assemblies and its application to molecular photodiodes [2,3] have been one of the main subjects of our laboratory. 

DiBenedetto SA, Facchetti A, Ratner MA, Marks TJ (2009) Molecular self-assembled monolayers and multilayers for organic and unconventional inorganic thin-film transistor applications. Adv Mater 21 1407-1433... 

Organic thin film (monolayer) coatings can be applied on oxide or metal (typically gold)-coated probe tips following recipes for self-assembled monolayer depositions that were adjusted for AFM probe technology. These probes are also commercially available and are useful to ensure known surface chemistry, to immobilize molecular species for assessing specific interactions, or to enable enhanced imaging conditions. 

SEIRA and SERS are powerful techniques for stmctural characterization of ultra thin films and well-ordered monolayer on metal surfaces. Thin films at interfaces are prepared by different procedures and developed for various applications. The fabrication and characterization of ultra thin films is a permanent area of research where some of the most interesting subjects are (a) bilayers and monolayers at liquid-liquid interface, (b) adsorption monolayers and Langmuir (water-insoluble) monolayers at air-water interface, (c) adsorption films and self-assembled monolayers (SAMs) at liquid-solid interface and Langmuir-Blodgett Alms, cast (deposit) films and spin-coat films at air-solid interface. Studies about molecular organization of monolayers of porphyrins derivatives, of azamacrocy-cles and their metallic derivatives among the many SEIRA applications to films and interfaces, were published . 

It is well known that the surface/interface of materials usually exhibits properties and behaviors that are considerably different from the bulk phase. The functionality of the soKd surface modified by an organic thin film, such as a self-assembled monolayer (SAM), Langmuir-Blodgett (LB) ultrathin film or polymer thin film, depends significantly on its surface molecular structure [1-4]. Therefore, elucidation and control of the surface molecular structure is essential to understand the novel functionality introduced by the modification. Most existing surface techniques require the sample to be placed in an ultrahigh vacuum (UHV) environment [5] and are therefore unsuitable for studies in either air or liquid. On the other hand, as comprehensively reviewed in this chapter, a number of modem instrumental analysis methods, such as infrared reflection absorption... 

Crown ether complexation emerged as a versatile molecular recognition principle to realize molecularly-organized thin film assemblies and nanoarehiteetures. Self-assembled monolayers (SAM), for example, were successfully employed to gain control over the organization of a Ceo derivative - bearing a crown ether functionality -and an ammonium-terminated alkanethiolate that was attached... 

Recently, Pcs organized on surface have been used as molecular probes for the determination of quantum confined effects [207], CoPc molecules form ordered self-assembled monolayers (SAM) on the top of Pb(lll) thin films grown on a Si( 111) substrate with the Pc units lying flat on the surface, as revealed by atomically resolved STM. A close analysis of the STM data revealed that the Pc molecules adsorb and self-assemble on the surface following a thickness-dependent adsorption pattern, which is ultimately related to the quantum size effects of the metal surface. 

Figure 19-2. Schematic overview of the type of apparatus used to investigate the desorption of ions and neutral species induced by electron impact on thin molecular and bio-organic films. In the case of thin DNA films, they are formed outside vacuum by lyophilization on a metal substrate or as a self-assembled layer. The films are placed on the multi-sample holder in the load-lock chamber. From there, they can be transferred one by one to the main chamber for analysis...

Abstract. The design and synthesis of new molecular synthons for vapor-phase self-assembled nanodieletrics and silane crosslinkers for crosslinked polymer blend dielectrics is described. These dielectric films exhibit excellent dielectric properties with tunable thicknesses and capacitance values. These new gate dielectric materials are integrated into thin-film transistors based both p- and n-type organic semiconductors. 

PFS block co-polymers in which the blocks are immiscible (which is generally the case) would be expected to self-assemble to form phase-separated organometallic domains in the solid state. Based on the classical behavior of organic block co-polymers, thin films of polyferrocene diblock co-polymers would be expected to form domains such as spheres, cylinders (or their anti-structures), double diamonds (or gyroids), or lamellae (Section 1.2.5). The preferred domain structure would be expected to be controlled by the ratio of the blocks, their degree of immiscibility (as defined by the Flory-Huggins interaction parameter y), and the overall molecular weight of the block co-polymer. 

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