Donor-acceptor compounds

Donor-acceptor compounds have been known for a long time [1] and their understanding has existed long on the basis of the acid-basis theory [2]. The appearance of a standard textbook in 1961 by Briegleb [3] had a great impact in this field, since it was a comprehensive review at this time. The modern understanding of donor-acceptor complex formation [4] or more general the nature of... 

Lippert E, Ayuk AA, Rettig W, Wermuth G (1981) Adiabatic photoreactions in dilute solutions of p-substituted N, N -dialkylanilines and related donor-acceptor compounds. J Photochem 17 237-241... 

Helms A, Heiler D, McLendon G (1992) Electron transfer in bis-porphyrin donor-acceptor compounds with polyphenylene spacers shows a weak distance dependence. J Am Chem Soc 114 6227-6238... 

Most of the available literature on ET studies in donor-acceptor compounds focuses on porphyrins. Phthalocyanine building blocks have been used less often38, a result of their low solubility and (until recently) the lack of appropriate synthetic methodologies to... 

In this chapter, we will discuss the recent results regarding the development of molecular switches and logic gates toward information processing at the molecular level based on electroactive molecules and supramolecules. Also, we will illustrate the progress of application of electron donor-acceptor compounds in high-density information storage. 

V,/V-Dimethylamino)benzonitrile (DMABN) and its derivatives, as a class of organic donor-acceptor compounds, exhibit dual fluorescence, one related to the local excited state ( B band) and the other ascribed to the twisted intramolecular charge transfer (TICT) state ( A band).17 As expected, compound 818 exhibits dual fluorescence, showing two fluorescence bands centered at 350 and 432 nm, which can be ascribed to the corresponding band (from the local excited state) and A band (from the TICT state), respectively. After oxidation of TTF unit in 8, the fluorescence intensity of A band decreases while that of band increases slightly. As expected, further reduction of TTF" + into neutral TTF unit leads to the restoration of the fluorescence spectrum of 8. Therefore, the dual fluorescence spectrum of 8 can be reversibly modulated by redox reactions of TTF unit in 8. 

The Notion of TICT States in Aromatic Donor-Acceptor Compounds... 

Unfortunately, 7 is a poor solvent for donor-acceptor compounds, and a maximum of 1 wt % concentration was achieved for 1. Limited solubility is a common problem with host-guest systems we found however, that the solubility of donor-acceptor stilbene and azobenzene compounds can be improved considerably by die attachment of bulky side-groups such as butyl or allyl to the chromophores. In this way, loading levels above 15 wt % were possible for certain compounds. On the other hand, simple cyclic side-groups such as pyrrolidino (12) led to poorly soluble materials (Figure 1). 

Ambiphilic derivatives, also called amphoteric derivatives, are polyfunctional compounds combining Lewis bases and Lewis acids (Figure 1). Such donor-acceptor compounds typically combine group 15 and 13 elements featuring, respectively, a lone pair of electrons and a vacant orbital. Among the possible combinations, phosphine-boranes (PB) clearly occupy a forefront position. 

The terms co-ordination compound, dative covalent compound, complex, or donor-acceptor compound are used synonymously for those compounds formed by the interaction of a molecule containing an empty orbital with one that possesses a filled orbital. The term complex was used to distinguish materials such as CoBr33NH3 from simple salts such as CoBr3. Notice the use of a dot to indicate some kind of a dative covalent interaction. The molecule or ion with the filled orbital is termed the donor and that with the empty orbital is called the acceptor. Examples are known in which only main group compounds are involved (Fig. 1-1). 

However, the most common examples of co-ordination compounds are those in which metals (and particularly transition metals) act as the acceptors. The metal may be in any oxidation state, and the donor-acceptor compounds may be neutral or charged (Fig. 1-2). 

Donor-acceptor-donor and acceptor-donor-acceptor compounds are promising for large values of S. 

Ethanol can be a donor capable of forming the donor-acceptor compounds with fullerene in the system involved. Donor will displace the solvent from the solvate shell when the ethanol content increases (to 30-50 vol. %) and high excess of the donor relative to the fullerene is obtained. 

Second order non-linear optical properties have been reported for a variety of TTF donor-acceptor compounds <02T7463> and the palladium complex 84 is a room-temperature semiconductor <02CL936>. Preparation of the zinc and cadmium compounds 85 has been reported <02CC1474> and aromatic fused TTFs such as 86 form thin films with useful electrical properties <02JAP265466>. A ferromagnetic interaction occurs in the salt of a TTF... 

Ogawa and coworkers have examined peptide y -strand mimics of the general type 24 (R = CH(CH3)2, n = 1-3), consisting of a ruthenium(II) polypyridyl electron donor tethered to a cobalt(III) pentammine electron acceptor by an polyvaline peptide chain [107]. A related parallel ) -sheet mimic has also been studied [108]. These compounds adopt the conformational properties found within the individual strands of a y -pleated sheet in both aqueous and methanol solutions. Emission lifetime measurements and HPLC product analyses suggest that the binuclear donor-acceptor compounds undergo photoinduced electron transfer. The values of et decrease with increasing donor acceptor distance according to y = 1.1 A, which is observed for electron transfers both in water at 298 K and in ethanol-... 

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