Polyacene

Step Number of units(rings) Number of atoms STO-3G 6-31G(d)  

As an application to bio-system, we applied our treatment to / -carotene as shown in the top of Table6.6. The two basis sets of STO-3G and 6-31g(d) were also implemented for the geometry optimized at HF/6-31G level to check the accuracy from starting cluster size of 6 units. The STO-3G results show around two-order improvement in the total energy by the new elongation method, while the 6-31G(d) results show around three-order improvement as seen in the case of polyacene. The errors caused by traditional elongation method become larger with basis sets size as seen from the table, while new treatment presented here is not so sensitive on the basis set used. 

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Pariser R 1956 Theory of the electronic spectra and structure of the polyacenes and of alternant hydrocarbons J. Chem. Rhys. 24 250-68... 

These batteries incorporate a polyacenic semiconductor (PAS) for the active material of the positive electrode, lithium for that of the negative electrode and an organic solvent for the electrolyte. PAS is essentially amorphous with a rather loose structure of molecular-size order with an interlayer distance of 4.0 A, which is larger than the 3.35 A of graphite [56, 57]. 

The batteries feature a high operating voltage of 2.0-3.3 V. The energy density of SL621 (diameter 6.8 mm, height 2.1 mm) is 6.5 Whl"1. It is applicable to various types of small, thin equipment requiring backup for memory and clock function. Table 15 shows the specifications of lithium—polyacene batteries [58],... 

Table 15. Specifications of secondary lithium-polyacene batteries...

Polyacene is classified as a material which does not belong to either soft or hard carbons [84], It is also made by heat-treatment of phenol resin. As the heat-treatment temperature is lower than about 1000 °C, polyacene contains hydrogen and oxygen atoms. It has a conjugated plane into which lithium ions are doped. It was reported that the discharge capacity of polyacene is more than 1000 mAhg. However, there are no practical lithium-ion batteries using polyacene. 

Naphthalenedicarboxylic acid is useful in the synthesis of linear polyacenes,8 3-halo-2-naphthoic acids,4 and 3-amino-2-naphthoic acid.4... 

Girreser U., Giuffrida D., Kohnke F. H., Mathias J. P., Philp D., Stoddart J. F. The Structure-Directed Synthesis of Cyclacene and Polyacene Derivatives Pure... 

These calculations have been conducted on the basis of RHF optimized geometries, considering the 6-31G basis set for the n-alkane compounds (11), and the 6-31G basis set for the polyacene series (12). In both cases, the basis set contention has been checked by comparison with more thorough investigations on small compounds, such as ADC[3] calculations (11a) on n-butane based on the 6-31IG, 6-31G and 6-31G basis, or the MRSDCI ionization spectrum of ethylene as obtained by Murray and Davidson (33) using a 196-CGTO basis set. 

Pyykko, P. and Zaleski-Ejgierd, P. (2008) From nanostrips to nanorings the elastic properties of gold-glued polyauronaphthyridines and polyacenes. Physical Chemistry Chemical Physics, 10, 114-120. 

The 327-670 GHz EPR spectra of canthaxanthin radical cation were resolved into two principal components of the g-tensor (Konovalova et al. 1999). Spectral simulations indicated this to be the result of g-anisotropy where gn=2.0032 and gi=2.0023. This type of g-tensor is consistent with the theory for polyacene rc-radical cations (Stone 1964), which states that the difference gxx gyy decreases with increasing chain length. When gxx-gyy approaches zero, the g-tensor becomes cylindrically symmetrical with gxx=gyy=g and gzz=gn. The cylindrical symmetry for the all-trans carotenoids is not surprising because these molecules are long straight chain polyenes. This also demonstrates that the symmetrical unresolved EPR line at 9 GHz is due to a carotenoid Jt-radical cation with electron density distributed throughout the whole chain of double bonds as predicted by RHF-INDO/SP molecular orbital calculations. The lack of temperature... 

Figure 12.1 Schematic series of aromatic polyacene molecules.

Because of this degeneracy and coexistence of these resonant structures one expects intrinsic conjugation defects to exist and be formed along the chain, the so-called Pople-Wamsley defects (34) which in the case of polyacenes and polydiacetylenes takes the form... 

Fig. 11 Correlation between electrochemical potentials and OMTS bands for more than ten compounds including polyacenes, phthalo-cyanines, and porphyrins. OMTS data were acquired both from tunnel junctions and STM measurements. The standard potential relative to the normal hydrogen electrode associated with the half reaction M(solution) + e-(vac) —> M-(solution) is the y axis. The three outliers are assigned to the ring oxidation of porphyrins. (Reprinted with permission from [26])...

Mazur U, Hipps KW (1994) Unoccupied orbital mediated tunneling resonance-like structures in the tunneling spectra of polyacenes. J Phys Chem 98 5824—5829... 

El-Sayed, M. A., Pavlopoulos, T. Polarization of the triplet-triplet spectrum of some polyacenes by the method of photoselection. J. Chem. Phys. 39, 834 (1963). 

Raghu, C., Anusooya Pati, Y., Ramasesha, S. Structural and electronic instabilities in polyacenes density-matrix renormalization group study of a long-range interacting model. Phys. Rev. B 2002, 65(15), 155204. 

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