Conjugated chromophores synthesis

Supramolecular Organization of -Conjugated Chromophores via Coordination Chemistry Synthesis of Analogues of [2.2]-Paracydophanes... 

The state of research on the two classes of acetylenic compounds described in this article, the cyclo[ ]carbons and tetraethynylethene derivatives, differs drastically. The synthesis of bulk quantities of a cyclocarbon remains a fascinating challenge in view of the expected instability of these compounds. These compounds would represent a fourth allotropic form of carbon, in addition to diamond, graphite, and the fullerenes. The full spectral characterization of macroscopic quantities of cyclo-C should provide a unique experimental calibration for the power of theoretical predictions dealing with the electronic and structural properties of conjugated n-chromophores of substantial size and number of heavy atoms. We believe that access to bulk cyclocarbon quantities will eventually be accomplished by controlled thermal or photochemical cycloreversion reactions of structurally defined, stable precursor molecules similar to those described in this review. 

An important challenge in the design of novel conjugated polymers is the synthesis of materials with tailor-made solid-state electronic properties. This section outlines the synthesis of the most significant classes of poly(para-phenylenevinylene)s (PPVs), poly(para-phenylene)s (PPPs), and related structures. Furthermore, this review demonstrates that the chromophoric and electronic properties of conjugated rr-systems are sensitive to their molecular and supra-molecular architecture. 

The literature of diene and polyene photochemistry provides many cases of synthetically useful reactions. As a result, certain arbitrary decisions have been made regarding what is covered in this chapter. For example, intramolecular [2 + 2]-photocycloaddition reactions of a, >-dienes can be formally included under the general rubric of diene photochemistry. However, we have chosen to restrict our discussion to dienes and polyenes which constitute a self-contained chromophore, viz. conjugated, cross-conjugated and 1,4-diene systems. Likewise, arene-olefin photocycloadditions will not be considered. These two broad classes of photoreactions have been applied extensively in synthesis, and have been the subject of recent reviews3,4. 

Chromophores based on aryl moieties can be easily grafted on to halophosphines via simple nucleophilic substitutions, as illustrated by the synthesis of 114 (Scheme 4.34). As a result, numerous phosphines bearing extended jt-conjugated substituents have been prepared. The aim of this section is not to give a comprehensive account of all derivatives that have been synthesized, but rather to illustrate how phosphorus fragments can be used either to influence or to organize the Jt-conjugated systems, with special emphasis upon fluorescence and NLO properties. 

Sun s group reported the synthesis, characterization, and photophysical properties of a series of organic receptors and their corresponding Re(I) tricarbonyl complexes as anion probes, featuring bis-sulfonamide as interacting sites attached to highly chromophoric Ji-conjugated quinoxaline moieties (see Fig. 18) [155],... 

The synthesis of tetraarylsilanes via Wurtz cross-coupling of bromoarenes and SiCU is a short and efficient route to tetraarylsilanes. Four conjugated units like biphenyl or naphthalene can be attached to the central silicon atom in high yield, but in the case of donor-substituted stilbenoid oligomers, this method gave only poor results [12]. For the preparation of tetrahedral silanes with phenylenevinylene chromophores, the convergent step was not performed on the central silicon atom but on a tetra- -tolylsilane (lb) functionalized with four phosphonic esters. The advantage of this approach is the additional extension of the n-system in the final step. 

The formation of new chromophores for the optimization of ultraviolet (UV) detection of analytes in HPLC implies the synthesis of derivatives with conjugated systems in the molecule. Compared with GC, there are no restrictions on the volatilities of these derivatives for HPLC analysis. They may be synthesized before analysis (precolumn derivatization) or after chromatographic separation (postcolumn derivatization). The latter technique is rarely used and then only for a few classes of compounds, but it permits us to... 

Chromophore systems of conjugated macroheterocycles 86MI21. Complexes of synthetic macroheterocycles, application in synthesis and... 

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