Chromophoric properties

Extended tetrathiafulvalenes with acetylenic cores are interesting compounds because of their redox and chromophoric properties. Such molecules are both interesting from materials and supramolecular chemistry perspectives. A tetraethynylethene-extended tetrathiafulvalene, for instance, was prepared using a microwave-promoted Sonogashira reaction [72]. Coup-... 

The chromophoric properties of triazolines permit the application of UV spectroscopy for kinetic measurements of formation and decomposition of the triazoline adducts.24,79,113,205 However, triazolines, when irradiated in the region of their UV absorption, undergo facile decomposition with nitrogen expulsion (Section IV,D,1).79,113... 

Zacks, D. N., Derguini, F., Nakanishi, K., and Spudich, J. L., Comparative study of phototactic and photophobic receptor chromophore properties in Chlamydomonas reinhardtii, Biophy. J., 65, 508, 1993. 

These additional bonds, which presumably are no longer localized, account for the chromophoric properties of the Si ring. This view is supported by the fact that a hypsochromic shift occurs when the free electron pairs of a substituent are blocked, for example, in an OR group by addition of BF3. 

Core-substituents have been shown to greatly influence the redox properties of NDIs, thus offering the possibility of a huge range of tunable fluorophores. In contrast, substituents at the imide position do not have any significant effect on the chromophore properties [19],... 

This work takes a completely different pathbased on the application of scientific tools unknown before the 1960 s, and still essentially unknown in the biological literature. It also incorporates a set of retinoid molecules into the theory of vision that can be shown to have the required chromophoric properties that Vitamin A aldehyde clearly does not possess. Neither retinol modified by a Schiff base nor further protonation of that Schiff base offers the required absorption spectrum18. 

Further extension of the chromophores in 25, by two anilinoethynyl groups (Figure 5), leads to a significant bathochromic shift of the longest-wavelength absorption band (Amax = 616 nm (shoulder), end-absorption 750 nm). Thus, the chromophoric properties of... 

In recent years nonlinear optical materials on the basis of nitroazoles, especially nitrobenzoxazoles and nitrobenzoxadiazoles, have investigated under intense scrutiny, at that and UV and fluorescence spectroscopy is widely used in studying of their structure and dynamics [1202-1225], 4-Aminosubstituted 7-nitrobenzofura-zans have a strong band in the visible region ( =457-483 nm) due to their chromophore properties [777]. 4-Substituted 7-nitrobenzofurazans possess a strong fluorescence that has led to their use as biochemical fluorescent probes in cell membranes [777, 1226-1228],... 

The presence of any of several functional groups is likely to impart photolability to drug molecules. These include carbonyl (C=0), nitroaromatic, -N-oxide, -alkene (C=C), aryl chloride, weak C-H and O-H bonds, sulfides, and polyenes. Some of these functional groups impart photolability as a result of their chromophoric properties (e.g., carbonyl) and some of them impart photolability by virtue of their weak covalent bonds, (e.g., O-H bonds). A list of several common bonds and their respective bond energies (E ) and the corresponding wavelengths ( ) are presented in Table 1. 

A comparison of the chromophoric properties of tetraselenoanthracenes and tetraselenophenanthrenes 8 and 32-35 is presented in Table 2 <1995JMC1539>. 

Fabrication of photoreactive organic thin films (POTF) requires the use of special chromophores that change their molecular structure and/or properties upon irradiation and thereby constitute the basic photoactive function. The changes in the chromophores properties should be adequately large to obtain a satisfactory response toward irradiation. It is not sufficient to have an... 

The tertiary hydrogen of the triamino compounds (leuco base) is easily oxidized to the carbinol (color base) which under the influence of hydrochloric acid dehydrates to form a highly colored hydrochloride. In the dehydration one of the phenyl groups rearranges to a quinonoic structure which has chromophoric properties ... 

There is a trend away from the study of particular molecules, such as benzene, which have been regarded as being examples of specific chromophore properties which are essential for a complete understanding of behaviour in more complex situations. Simple molecules are however still important subjects for research. The lifetimes of AgO molecules in rare gas matrices have been... 

Hydroxides are often used for precipitation of traces with collectors [72-74]. With Fe(III), Al, or La as collector, traces of most analytical group I-III metals are separated by addition of excess of ammonia. Metals forming ammine-complexes, e.g., Ag, Cu, Ni, Co, Zn, and Cd remain in solution. When excess of NaOH is used for precipitation, amphoteric metals such as Al, Pb, Zn, Sn, and Cr remain unprecipitated. In this case, Fe(III), Ti, Mg, or La may be used as the collector. Lanthanum is especially convenient, since it usually does not have to be determined in the trace concentrate. It has no chromophoric properties and it does not interfere in most spectrophotometric methods. 

Ethylenediaminetetraacetic acid (EDTA, formula 17.2) forms coloured complexes with cations which have chromophoric properties (e.g., Fe, Cr, Cu, Co, Ni). These complexes, which are not very intensely coloured, form the basis of several less sensitive spectrophotometric methods, such as that for chromium(III)... 

RSSF studies of the LADH-catalyzed interconversion of 3-hydroxy-4-nitro-benzaldehyde and the corresponding alcohol have provided additional insights into the electrostatic properties of the LADH catalytic site and substrate binding cleft (20, 21,33). The chromophoric properties of the 3-hydroxy-4-nitrobenzyl... 

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