Conjugated benchmarking

X-Ray crystal structure analyses of both squaric acid158 (3,4-dihydroxy-3-cyclobutene-l,2-dione) and the dianion159 are the usual benchmarks used in consideration of structural data of metal complexes. The relevant dimensions are shown in Table 9, from which it can be seen that there is substantial conjugation and C2 symmetry in the acid molecule while the dianion has DAh symmetry... 

The rate-determining step always corresponds to protonation or deprotonation of a carbon atom, while equilibration of oxygen acids with their conjugate bases is established rapidly. This fact can be used to determine the acidity constants of enols, ynols and ynamines by flash photolysis, Kf, either kinetically, from downward bends in the pH rate profiles indicating a pre-equilibrium, or from the changes of the transient absorption in solutions of different pH (spectrographic titration). Such studies have provided some remarkable benchmark numbers, such as the acidity constant of phenylynol (pKf < 2.1),476 phenylynamine (pKf < 18.0)477 and its pentafluoro derivative (pKf = 10.3),478 and of the carbon acid 2,4-cyclohexadienone, pKf = —2.9 475 The enolization constant of 2,4-cyclohexadienone is pKE = 12.7. 

In our contribution, we address this aspect and describe numerical methods based on the use of efficient iterative solvers, which exploit the conjugate gradient (CG) method, its generalization and the space decomposition preconditioners. The efficiency of these solvers will be illustrated by the solution of elasticity and thermo-elasticity problems arising from the finite element analysis of selected benchmarks with computations performed on a PC cluster. The introduced ideas could be useful also for the solution of more complicated coupled problems. 

The conjugated polymers we will focus on in this chapter are soluble polythiophene as shown in Figure 9.1, which include poly(3-butylthiophene) (P3BT) [7-9], P3HT [7-9], and poly(3,3" -didodecylquaterthiophene) (PQT-12) [10]. This class of conjugated polymers includes the benchmark semiconductor materials for flexible electronics. 

Why are acid-base properties presented for alkanes The answer is because it is important to define relative acidity as it relates to other compounds. Establishing that alkanes are considered to be extremely weak acids or bases gives a benchmark for categorizing other weak protonic acids and bases. In Chapter 15, a reaction will be discussed that generates an alkane as a conjugate acid. Categorizing alkanes as very weak acids rather than nonacids will help explain that reaction (see Sections 15.3 and 15.5.2). 

Addition of 1, 5, or 10 % of selected MP-oligothiophene conjugates to the blend allowed increasing the PCE of the SC compared to that of the P3HT PCBM benchmark material not containing porphyrins (Table 29). 

Allylic alkylation is probably the only reaction that could dispute the honorific title of benchmark test for new chiral NHCs to conjugate addition. In fact, most chiral NFICs are tested in both reactions and, as a consequence, main advances in both topics have come from the same research groups. This chemistry was thoroughly reviewed by Mauduit and Douthwaite, from Okamoto s first report to the year 2007. 

Many low molecular weight benchmark structures such as adamantane (1), dia-mantane (2) as well as the next several higher diamondoids (3-6), cubane (7), al-lene (8), propyne (9), benzene (10), naphthalene (11), and anthracene (12) (Scheme 8.1) are not all carbon-rich per definition but they serve as excellent models to test the underlying theory and to extrapolate to the much larger carbon-rich, often infinite stmctures. A further distinction can be made according to hybridization, whereby conjugated (sp and sp ) structures are best put in one category and non-... 

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