Appended systems incorporating

In 2004, Rayner and coworkers reported a dynamic system for stabilizing nucleic acid duplexes by covalently appending small molecules [34]. These experiments started with a system in which 2-amino-2 -deoxyuridine (U-NH ) was site-specifically incorporated into nucleic acid strands via chemical synthesis. In the first example, U-NH was incorporated at the 3 end of the self-complementary U(-NH2)GCGCA DNA. This reactive amine-functionalized uridine was then allowed to undergo imine formation with a series of aldehydes (Ra-Rc), and aldehyde appendages that stabilize the DNA preferentially formed in the dynamic system. Upon equilibration and analysis, it was found that the double-stranded DNA modified with nalidixic aldehyde Rc at both U-NH positions was amplified 34% at the expense of Ra and Rb (Fig. 3.16). The Rc-appended DNA stabilizing modification corresponded to a 33% increase in (melting temperature). Furthermore, imine reduction of the stabilized DNA complex with NaCNBH, resulted in a 57% increase in T. ... 

Figure 23 lists representative acid-labile protecting groups that have been incorporated in positive-tone CA resist systems. These groups can be pendent to the matrix polymer chain, can be attached to a monomeric or polymeric additive that acts as a dissolution inhibitor (64—66), or can even be appended to the PAG structure (67). The kinetics of acid-catalyzed deprotection vary significantly with structure. In particular, the activation energy,... 

The first ester functionalized cobaltocenium receptor (74) developed by us in 1989, was based solely on electrostatic interactions (as discussed earlier) (9, 186). It was therefore decided to append the cobaltocenium moiety with secondary amide functionalized arms . In this manner, the receptors became more resistant to hydrolysis (a recurrent problem with ester-based systems), and also incorporated neutral hydrogen-bond donors capable of coordinating anions. [An interaction between a secondary amide (acetamide) and the bromide anion was physically investigated (by IR spectroscopy) as long ago as 1961 (211)]. We made the first report of this novel type of receptor (91 and 92) in 1992 (212), which was, in fact, the first class of inorganic anion receptor that incorporated hydrogen-bonding functionalities. 

Lower rim derivatization is far easier to effect and examples include alkyl-, ester-, amide-[4], pyridyl- [5] and pyrene-appended [6] systems, not to mention the more exotic species that bind gallium [7] or give a colorimetric response when complexing chiral guests [8] as shown in Figure 3.19. Further examples include oxacalix[3]arenes that form capsules [9,10], palladium cross-linked dimers [11-13] and 2 1 inclusion complexes with C6o [14,15]. Oxacalixarenes with lower rim substituents have even been incorporated into electrochemical sensors for... 

Compared to systems based on a single interaction, cooperative sensors based on multiple, concerted, inter-molecular interactions between the components exhibit higher discrimination capabilities and enhanced functions. As examples for this class of sensors, two systems, both based on the absorption/luminescence properties of the porphyrin nucleus are illustrated in Fig. 5. Structure (a) represents a ditopic receptor where cooperative binding of a cation by the amide-appended calixarene and of an anion by the Zn-porphyrin allows recognition of complete binary metal salts. Structure (b) incorporates two cyclodextrin cavities and relies on the modification of the Fe(III) complex spectroscopic properties by inclusion of guests in these hydrophobic sites.This species is able to sense the presence of benzylmercaptane and 1-adamantanecarboxylate in four... 

Current systems require many steps to include graphical objects and other non-textual entities into documents. The new systems will support easy incorporation of multiple data types (e.g., chemical structures, reaction schemes, graphs, charts, data tables, etc.) while retaining the characteristics of the objects. One will be able to manipulate the object in its native mode and append ancillary data to the document if desired. 

We recently initiated efforts within our own laboratory to synthesize terpy-based ligands that incorporate appended Lewis acid/base pairs [36]. Motivated by metal-free systems of frustrated Lewis pairs (FLPs) which bind and form adducts with small molecules, we sought to couple the reactivity of FLPs to a transition-metal fragment to afford a metal Lewis acid/base triad (LABT). The combination of both partners with a transition-metal center opens up the possibiUty to synergistically use these systems for further activation and/or redox transformations - currently a hmitation of metal-free FLP systems. 

As carbene complexes have become proficient catalysts, their incorporation into recyclable catalyst systems has grown into a field of its own. The most common strategy for recovering a catalyst for subsequent use is to append it to a heterogeneous support (e.g., a PS bead), and both Fischer carbenes and NHCs have been incorporated into polymers for this purpose. The first polymer-bound Fischer carbene complexes were reported by Mariorana and Seneci in 1999 [51], for use in soHd-phase organic synthesis for combinatorial chemistry. These materials were prepared via the attachment of chromium carbene complexes to a polymer resin... 

A convenient way to append a transition metal to any organic molecule is making use of a cyclam ring. This 14-membered tetramine macrocycle incorporates 3d metal ions, to give complex species that are very stable both in a thermodynamic and a kinetic sense. Moreover, the firmly encircled cation keeps or enhances the interesting features typically presented by transition metals redox activity through fast and reversible one-electron transfer processes, affinity towards ligands (which will go to occupy the two axial positions left available by the co-planarly coordinated tetra-aza macrocycle). Thus, on reaction of 9-bromomethylanthracene with an excess of cyclam, the two-component system 4 was obtained (cyAn). 

---