Dichlorobenzenes, absorption spectra

The absorption spectra characteristic of the benzene rings in the region of 700-900 and 1600 cm l remain rather intense when all the other bands decrease in intensity or disappear. This gives evidence that the residue after destruction is enriched in phenyl rings. The infrared spectra of the destruction products of the polyarylate TD obtained are definitely similar in the region of 700-900 and 1600 cm to the infrared absorption spectrum of the pol3q)henylene obtained from dichlorobenzene (Fig. 148). 

Another important consideration is the boiling point (BP) of the solvents. The BP determines how quickly the solvent evaporates and thereby the formation rate for polymer and fullerene domains. Polymer domains that equilibrate slowly in high BP solvents tend to be more crystalline (thermodynamic product) whereas low BP solvents evaporate quickly and yield mixed amorphous films (kinetic product). When spin-coating at 1,000 rpm, a 20 mg/mL solution of 1 1 P3HT PCBM condenses to a film in 1-3 s when processed with CHCI3 (BP = 61°C), 5-10 s when processed in chlorobenzene (BP = 132°C), and the film remains wet after 60 s when processed with 1,2 dichlorobenzene (BP= 182°C) (Moule, personal observation) [70]. The change in structural order in P3HT is observed in a red shift of the absorption spectrum and formation of a clearly defined vibronic structure [71]. 

In dichlorobenzene, the determination of UV/Vis spectrum of 463 showed three absorption maxima at 374, 394, and 415 nm (99MI2095). 

In hot, dilute dichlorobenzene solutions (>50 °C) broad absorption at Amax 480 nm is apparent in the UV-visible spectrum of PQT-12 (Fig. 4.8a), but the absorption is slightly red-shifted with the concomitant appearance of weak absorption at A max 610 nm (Fig. 4.8b) when the solution is cooled to room temperature. This is obviously because of the migration of PQT-12 molecules from the twisted disordered conformation in hot solution to an ordered coplanar conformation at lower temperatures. Because the HOMO level of PQT-12 in the solid state, esti-... 

Figure 1 UV-visible absorption spectra of matrix-isolated p-dichlorobenzene and of its radical cation (a) spectrum of p-dichlorobenzene before photolysis (b) spectrum after 15 min photolysis at = 220-1000nm (c) spectrum after 15 min Ar resonance photolysis. The much increased yield of product upon vacuum UV photolysis can clearly be seen. (Reprinted with permission from Friedman et al., J. Phys. Chem., 1984, 88, 1944. 1984 American Chemical Society)...

When sublimed, anthraquinone forms a pale yellow, crystalline material, needle-like in shape. Unlike anthracene, it exhibits no fluorescence. It melts at 286 0 and boils at 379 —38UC. At much higher temperatures, decomposition occurs. Anthraquinone has only a slight solubility in alcohol or benzene and is best recrystaUized from glacial acetic acid or high boiling solvents such as nitrobenzene or dichlorobenzene. It is very soluble in concentrated sulfuric acid. In methanol, uv absorptions of anthraquinone are at 250 nm (e = 4.98), 270 nm (4.5), and 325 nm (4.02) (4). In the ir spectrum, the double alljdic ketone absorbs at 5.95 am (1681 cm ), and the aromatic double bond absorbs at 6.25 im (1600 cm ) and 6.30 Jm (1587 cm ). 

In this context, dialdehyde la (5 mg, 0.017 mmol), sarcosine (14 mg, 0.157 mmol) and five-fold excess of Ceo (60 mg, 0.083 mmol) dissolved in 10 ml of o-dichlorobenzene (o-DCB) heated at 130 °C for 90 min. After a typical work up procedure, the reaction mixture is purified by recycling HPLC on a preparative Buckyprep Cosmosil column (250 X 20 mm, toluene eluent, lOml/min flow rate) to furnish bis-fullerene derivative 3 in 32 % yield. The bis-fullerene 3 shows moderate solubility, thus allowed us to record and NMR spectra (Supp. Info., Fig. SI) corroborating the depicted structure in Scheme 1. The attenuated-total-reflectance infra-red (ATR-IR) spectrum of 3 demonstrates the characteristic stretching vibrations of the C-H (2803-3030cm" ) as well as the characteristic absorptions for fullerenes (Supp. Info., Fig. S2). Matrix-assisted-laser-desorption time-of-flight mass-spectroscopy (MALDI-TOF-MS), in the negative ionization mode and with the aid of trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile shows the molecu-... 

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