Dendrimers structural components

In this fashion, it is possible to control the critical molecular design parameters (CMDPs, i.e., size, shape, topology, flexibility, and surface chemistry) and grow predictable, stoichiometric structures up to a self-limited dimension (generation) which is determined by Nc and Nb as well as by the dimensions of the structural components. Such space-filling, terminally functionalized molecular organizations have been coined Starburst dendrimers [2]. Two dimensional projections of such molecular morphogenesis [1] are as illustrated in Fig. 2. 

In both cases, the luminescence of the species A is quenched, and in the case of energy transfer, it can be replaced by the luminescence of species B (sensitization process). In dendrimers, energy- and electron-transfer processes can also occur among nearby molecular components incorporated in the dendrimer structure. For example, in a dendrimer containing A and B component units, excitation of A may be followed by energy (Eq. 10) or electron (Eqs. 11 and 12) transfer to B (5) (Fig. 3b) ... 

Three structural components are common to all dendrimers a core unit, peripheral groups, and the multiple branching units that span the two. The core unit in dendrimers is usually an important part of the structure as it covalently links the dendritic wedges (dendrons). However, cored dendrimers have been... 

This chapter presents a selective glimpse of this dynamic family of spherical macromolecnles for newcomers to the topic in order to help them better appreciate the field that has been extensively reviewed elsewhere. This chapter is divided into several parts to emphasize the structmal diversity and their potential applications. First, a study of the internal structure of the dendritic architecture, emphasizing the different types, followed by a study of their interactions with other molecules or atoms, such as in the case of host-guest chemistry, molecular recognition, or encapsulation inside the dendrimer. Finally, there is a small section that will address the intermolecular interactions of dendrimers and dendrons to either themselves or other nano-objects. In this past quarter century, tens of thousands of papers have been published producing a wide variety of different dendritic architectures with varied structural components capable of novel supramolecular interactions. Therefore, only an overview describing their structure with representative examples and practical purposes will be discussed, when appropriate. 

In this review, we tried to cover all the supramolecular species that maybe classified as rotaxane dendrimers. We classified them by their structures - where in dendrimer rotaxane-hke features are introduced. Several different types of macrocycles have been employed as a ring component in the templated synthesis of rotaxane dendrimers. While the synthesis of Type I and II rotaxanes dendrimers is relatively straightforward, that of well-defined Type III rotaxane dendrimers, particularly those of second and higher generations, is still challenging. 

In particular, rotaxane dendrimers capable of reversible binding of ring and rod components, such as Type II, pseudorotaxane-terminated dendrimers, can be reversibly controlled by external stimuli, such as the solvent composition, temperature, and pH, to change their structure and properties. This has profound implications in diverse applications, for instance in the controlled drug release. A trapped guest molecule within a closed dendrimeric host system can be unleashed in a controlled manner by manipulating these external factors. In the type III-B rotaxane dendrimers, external stimuli can result in perturbations of the interlocked mechanical bonds. This behavior can be gainfully exploited to construct controlled molecular machines. 

In conclusion, the electrochemical data offer a fingerprint of the chemical and topological structure of these dendrimers. Furthermore, the knowledge of the electrochemical properties of the mononuclear components and the synthetic control of the supramolecular structure allow the design of dendrimers with predetermined redox patterns. 

The synthesis and structure of a dendrimer can be illustrated by the well-known poly (amidoamine) type (called PAMAM), which describes the monomers making up the complete polymer. The synthesis starts from a core diamine (or ammonia) molecule. The diamine can be of various lengths and spacer arm properties and even contain cleavable components. Typically, the core... 

In contrast to traditional polymers, dendrimers are unique core-shell structures possessing three basic architectural components namely, (I) a core, (II) an interior of shells (,generation) consisting of repetitive branch cell units and (III) terminal functional groups (i.e. the outer shell or periphery) as illustrated in Figures 1.13 and 1.14. 

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