Encapsulated complexes, review

With these caveats, then, the following is intended to illustrate the synthetic strategies to encapsulate complexes, rather than to comprehensively cover the field, which has been the subject of several reviews [140-142]. 

Much work with encapsulated complexes mainly in zeolites appeared in the past decade. Surprisingly, the last few years, a revival of the activity in this area has occurred, mainly by groups that entered the field rather recently. As this area is often reviewed as part of larger reviews on catalyst immobilization, this particular area of Complex Immobilization in Microporous Hosts usually is treated in less detail [2]. It is the aim of the present work, given the clear revival of activity in this area, to critically overview the major achievements. Emphasis will be on such complexes which have catalytic potential. The very early work, which appeared in the late seventies-early eighties, dominated by the Lunsford group, will only occasionally be referred to. It is hoped that this approach will help new workers to define new objectives and approaches. 

The chemistry of supramolecular polymers has been extensively reviewed [5], In the past two decades, general overviews as well as more specific surveys have focused on individual classes of polymers or on the mechanisms and thermodynamics of supramolecular polymerization. The present chapter aims to retrace the genesis and the evolutiOTi of that subgroup of supramolecular polymers that share the calix[5]arene skeletmi as their common building block. To this end, relevant examples of dimeric capsules and/or encapsulation complexes key to the subsequent design of polycapsular AA/BB-type arrays, as well as discoveries pivotal to an effective self-assembly of AB-type architectures are surveyed in parallel. 

Metalated container molecules can be viewed as a class of compounds that have one or more active metal coordination sites anchored within or next to a molecular cavity (Fig. 2). A range of host systems is capable of forming such structures. The majority of these compounds represent macrocyclic molecules and steri-cally demanding tripod ligands, as for instance calixarenes (42), cyclodextrins (43,44), and trispyrazolylborates (45-48), respectively. In the following, selected types of metalated container molecules and their properties are briefly discussed and where appropriate the foundation papers from relevant earlier work are included. Porphyrin-based hosts and coordination cages with encapsulated metal complexes have been reviewed previously (49-53) and, therefore, only the most recent examples will be described. Thereafter, our work in this field is reported. 

The encapsulation of classical and organometallic transition-metal complexes to yield molecules of the type complex in a complex is a very attractive research area. A variety of inclusion complexes of this type has been reported. Of relevance for this review are reports on the encapsulation of coordinatively unsaturated transition-metal complexes inside self-assembled coordination cages (120), cyclodextrins (121,122), and cucurbiturils (123). 

This chapter describes the synthesis, properties, and biomedical applications of cyanine and squaraine dyes encapsulated in CDs, CBs, Leigh-type tetralactam macrocycles, aptamers, and micro- or nano-particles. The optical and photochemical properties of supramolecular guest-host nanostructures that are based on intra-and intermolecular complexes of crown-containing styryl dyes with metal cations, and aggregates of carbocyanine dyes are discussed in a separate review [18]. 

Success in complexing laiger oiganic cations through encirclement or encapsulation by crown ether receptors is enhanced when benzo rings are lused on to the 3n-crown-n framework, as in 3-6. Three examples are worthy of brief consideration in the context of this review. 

Since the first report of dendrimer-encapsulated Cu nanoparticles [15], several types of mono and bi-metallic DENs have been prepared. DEN synthesis has been recently reviewed [9,16], so only the synthesis of bimetallic DENs is described here. Bimetallic DENs can be prepared by one of three methods co-complexation of metal salts, galvanic displacement, and sequential reduction. Several bimetallic systems have already been prepared inside PAMAM dendrimers Table 1 summarizes the current literature and synthetic methods employed. 

Photochemical processes of CD complexes,1 Differences in photochemical reactions conducted in solution and in CD complexes have been reviewed. For example, photo-Fries rearrangement of phenyl esters in solvents results in a mixture of o- and p-phenolic ketones via a radical reaction. Rearrangement of the same encapsulated ester results in exclusive rearrangement to the ortho-position (equa-... 

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