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Benzylic amide-based interlocked molecular architectures are becoming important players in the super-molecular field. They take the form of either catenanes or rotaxanes (which are not true supramolecular systems since the separation of the two independent molecules requires breaking of a chemical bond). Subsequent to their synthesis, much effort carried out by several groups has been aimed at measuring, understanding, controlling and directing the dynamics of unique degrees of freedom that arise from the formation of the mechanical bond between the two systems where either one ring is threaded through the cavity of another or the same ring is locked onto a dumbbell molecule. Here I present a review of the computer modeling performed in recent years on these systems with the final aim of discussing the recent unidirectional rotation that has been achieved for a very special catenane composed by three interlocked rings. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

In order to explore an ability to use alkyl-substituted porphyrins and phthalocyanines as a template for the immobilization and arrangement of various kinds of useful functional molecules, we examined the stability of self-organized 2-dimensional structures of alkyl-substituted porphyrins (C12OPP and C18OPP) and phthalocyanines (CuPcOC8) formed on graphite surface. We considered the stability of the self-organized 2-dimensional structures on the basis of the desorption law. The magnitude of total activation energy for desorption became large in order of C12OPP, CuPcOC8, and C18OPP. The difference in the total desorption energy correlates with the domain sizes of each molecule observed by scanning tunneling microscopy (STM). The fine STM images of mixture of C18OPP and pyridine-coordinated C18OPP rhodium chloride, which used as a substitution of useful functional molecules, indicate that alkyl-substituted porphyrin and phthalocyanine molecules are useful as a template for the directed arrangement of various kinds of useful functional molecules, such as rotaxanes. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The progress made in the modelling of the properties of benzylic amide-based interlocked molecular architectures is reviewed. It is based on the extensive use of molecular mechanics, molecular dynamics, quantum mechanical models and quantum chemistry. The simulations show in detail the role played by interlocking in the modification of a number of properties. [ABSTRACT FROM AUTHOR]

Nanotechnology is an area of study involving different disciplines, constituting wide and different devices groups derivative of engineering, biology, physics as well as chemistry. Enhancement in Engineered Nanoscopic scale materials utilization for biomedical implementations as well as improved treatment is because of the latest developments in the fields of nanotechnology and biotechnology. In medical nanorobotics, physics is utilized on the nanoscopic scale for the execution of advanced work abilities in robotic agents free from tether proposed for eventual operations in limited physiologic surroundings of the human body. In lab circumstances, nanorobots can carry material to specific locations, in the organisms, this is the result of comprehensive research and accelerated advancement regarding the biomedical utilization of nanorobots. On the micro-scale, nanorobots can carry out several chores, for instance, less intrusive diagnostics, cure of illnesses, delivery of the drug to specific parts as well as local surgical procedures. Even if there are advancements, there is finite research concerning liabilities associated with nanorobots as well as the discussion is finite about the possible control of nanorobots. [ABSTRACT FROM AUTHOR]

Light-induced processes are at the basis of fundamental natural phenomena as well as of a variety of applications. Since the functions that can arise from the interaction between light and matter depend on the degree of complexity and organization of the receiving ‘matter’, the research on these processes has progressively moved from molecular to supramolecular (multicomponent) systems, thereby originating the field of supramolecular photochemistry. In this context, examples of photochemical molecular devices and machines—that is, multicomponent chemical systems capable to perform specific functions under light stimulation—have been developed. Here we describe two recent examples of such systems based on pseudorotaxane and rotaxane species. These studies are of interest not only for the growth of nanoscience, but also for increasing the basic understanding and testing current theoretical treatments of photoinduced processes. [ABSTRACT FROM AUTHOR]

The nanok calculus has been recently introduced in [1] as a tool for the modeling and simulation of the behaviour of nano devices. Its basic components are molecules specified in terms of an interface and a set of fields. The interface is used to represent the bonds between the specified molecule and the other molecules in the nano device. The fields, on the other hand, describe the internal state of the molecule. The dynamics is modeled by means of reactions defined in terms of rewriting rules applied to pairs of abstractly specified molecules. In this paper we discuss the comparison between the nanok specification and the traditional specification of a two-station rotaxane [2], a versatile molecular shuttle currently used as a building block for more complex nano devices. [ABSTRACT FROM AUTHOR]

A novel symmetrical macrocycle has been synthesised via oxidative homocoupling of bisalkyne, diprop-2-ynyl pyridine-2,6-dicarboxylate mediated by copper (I) iodide (CuI) and 4-dimethylaminopyridine (DMAP). The precursor compound was synthesised from 2,6-pyridine dicarbonyl dichloride and propargyl alcohol in the presence of triethylamine. The reaction mixture was stirred overnight and further purified via column chromatograpy with 76% yield. Single crystal for X-ray study was obtained by recrystallization from acetone. Subsequently, a symmetrical macrocycle was synthesised from oxidative homocoupling of precursor compound in open atmosphere. The crude product was purified by column chromatography to furnish macrocycle compound with 5% yield. Both compounds were characterised by IR, ¹H and 13C NMR and mass spectral techniques. The unusual conformation of the bisalkyne and twisted conformation of designed macrocycle has influence the percentage yield. This has been studied thoroughly by X-ray crystallography and electronic structure calculations. [ABSTRACT FROM AUTHOR]

Understanding, using, and predicting the macroscopic properties of photoresponsive materials employed in technology and nature increasingly centers on the question what their photophysical and photochemical properties are at the molecular level, and how these properties can be addressed and influenced in a controllable way. High-resolution spectroscopy can in principle provide such a detailed picture of the electronic structure and dynamics of excited states, but requires at the same time often the development of novel experimental techniques to meet current demands on the size of the systems that can be studied and the level of detail. Furthermore, a multidisciplinary approach in which quantumchemical calculations play a prominent role is necessary to fully take advantage of the experimental results. [ABSTRACT FROM AUTHOR]

The semiconductor industry continues to fabricate integrated circuits (ICs) with faster clock speeds, increased numbers of transistors, and smaller feature sizes. A complete set of the attributes describing a new technology generation (or node) is specified by an important features size such as the 1/2 pitch of the first level of metal lines in a dynamic random access memory (DRAM). Historically, Moore’s law has been used to describe the timing associated with the three-year cycle of new generations of memory devices. Recently, the introduction of new generations of logic devices has surpassed the three-year node cycle of memory devices. New technology generations have another significance. Each generation requires a new set of manufacturing equipment and, recently, new materials. The International Technology Roadmap for Semiconductors (ITRS) describes the technology requirements for volume manufacturing of integrated circuits (ICs) for each new technology node over the next 15 years [1]. In the 15-year horizon of the current ITRS, industry experts are considering the possibility of a revolution in microelectronics. The ITRS predicts that the gate length of transistors at the end of the roadmap will be less than 10 nm. The ITRS also discusses the need to move beyond traditional planar CMOS during the next 15 years and the potential need to move into revolutionary technologies at the end of the roadmap. The physical properties of materials change from bulk-like into “nano-like.” For example, on-chip interconnects will have dimensions that have nanowire properties. The development and manufacture of new generations of ICs or their successors will require new measurement technology. There will be many different challenges for metrology over the next 15 years. This paper describes these challenges. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report on the structural and dynamic characterization by solid state NMR of a new rotaxane consisting of a thread molecule enclosed by a macrocycle, which can eventually shuttle or rotate along/around the thread. Different kinds of slow and fast motions are detected in the methylated exopyridine anthracene rotaxane by ¹H, [sup 13]C and [sup 19]F relaxation time versus temperature measurements. Analysis of the proton decoupled and temperature dependent [sup 19]F NMR spectra gives some indications of the possible motions of the macrocycle and breaking of the hydrogen bond in the solid-state at temperatures above 360K. [ABSTRACT FROM AUTHOR]

The concept of (macroscopic) device can be extended to the molecular level. A molecular-level device can be defined as an assembly of a discrete number of molecular components designed to achieve a specific function. A molecular-level machine is a particular type of molecular-level device in which the component parts can display changes in their relative positions as a result of some external stimulus. The extension of the concept of a device to the molecular level is of interest not only for basic research, but also for the growth of nanoscience and the development of nanotechnology. A few examples of molecular-level devices and machines are illustrated. [ABSTRACT FROM AUTHOR]