Beltlike Aromatic Hydrocarbons by Metathesis Reaction with Tetradehydrodianthracene

Abstract

COMMUNICATIONStemperature with occasional agitation. The supernatant was separated by ultrafiltration (Centricon, Amicon, cut-off 30 kDa, 6 h at 15 "C). The nanotubes were then washed with water (0.6 mL), and the separation was repeated. In a control experiment (to check for adsorption of DNA onto the membrane filter), DNA solution was added to the ultrafiltration tube in the absence of nanotuhes, and the separation and washing steps carried out as before. DNA concentrations were determined from the absorption at 260 nm. The recovery of DNA in the control experiment was >87%. A second set of experiments was carried out with 0.1 M NaCIO, to wash the tubes, and then melting curves for the desorbed DNA were determined by UV. Molecular rnodelmg: A bifunctional Pt adduct was constructed on one strand of a B-DNA model with the HyperChem program [19] and restrained energy minimization, followed by docking of the ammine ligands in an appropriate geometry. This produced a model of the bifunctional adduct similar to those obtained with Newton-Raphson energy minimization and a force field developed for PtiDNA interactions [20]. Iodine atoms were then added to the 5-positions of each cytidine base.

Naphthocyclobutenes and Benzodicyclobutadienes: Synthesis in the Solid State and Anomalies in the Bond Lengths

“…[40] The values calculated by the Becke 3LYP/ 6-31G* method for 64 (1.700 Å ) and 65 (1.721 Å ) are also comparable to those observed. [40] The latter calculation method is also applicable to 13a and the resulting bond lengths of 1.710(5)-1.724(5) Å are comparable to those observed (1.720 Å ). [39] The calculated value for 13a with B3LYP/6-31G* is also in good agreement with the experimental data.…”

“…Refinement of this highly accurate data set converged on a C-C bond length of 1.710(2) Å , in excellent agreement with the value (1.720 Å ) determined from the room temperature data. [39] The C ( [40] Theoretical calculations of the bond length for 64 (1.671 Å ) and 65 (1.703 Å ) by the PM3 method support the experimental data. [40] The values calculated by the Becke 3LYP/ 6-31G* method for 64 (1.700 Å ) and 65 (1.721 Å ) are also comparable to those observed.…”

“…[39] The calculated value for 13a with B3LYP/6-31G* is also in good agreement with the experimental data. [40] This calculation suggests that the long bond in 59 is 1.667 Å . [41] Computations [B3LYP/dz(2d,p)] on 1,1,2,2-tetraphenylbenzocyclobutene (66), which is a suitable model for 13a, in a C 2 conformation similar to that found crystallographically for 13a predict a bond length of 1.708 Å , in excellent agreement with the experimental observation for 13a.…”

Design and Synthesis of Carbon Nanotube Segments

“…However, [ 8]- [13]CPPs were obtained randomly at elevated temperatures,d epending on the reaction time.Y amago and co-workers achieved an unexpected size-selective synthesis of [10]CPP (Scheme 19). [38] Theh omocoupling reaction of Lshaped platinum complex 86 was attempted to obtain cyclic dimer,trimer, and tetramer as precursors for [8] Theg roups of Jasti and Yamago independently reported almost simultaneously the synthesis of [5]CPP,w hich is the smallest isolated [n]CPP to date.Inthe synthesis of [5]CPP by Jasti and co-workers (Scheme 20), [40] ahomocoupling reaction between the C À Bb onds of 54 b provided macrocycle 96 a.…”

Concise Synthesis and Crystal Structure of [12]Cycloparaphenylene

“…[1][2][3] Even though the bottom-up chemical synthesis of this simple molecular entity had been recognized as a Holy Grail in synthetic chemistry, [1,4] three groups including our own have recently succeeded in synthesizing some [n]CPPs. [5][6][7][8] Although these studies from the three research groups established the synthetic viability of the long-awaited CPPs, important issues remain unresolved (Scheme 1).…”