Electronic spectra of compounds with a three-atom conjugated system

Conclusions The behavior of absorption bands was examined for compounds with three-atom conjugated systems. The applicability of Dewar's rule was shown for compounds with carbon, nitrogen, oxygen, and fluorine. The proper prediction of the band behavior for other compounds requires consideration of the resonance integrals, unoccupied orbitals, and changes in the direction of electron cloud migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1407–1409, June, 1989.     

Electronic spectra of compounds containing the conjugated tetratomic system X(V)Y=Z

The correlation of the spectra of conjugated tetratomic and triatomic systems was examined by means of corrected Dewar rules.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1353–1356, June, 1992.     

New magnetic properties of macromolecular compounds containing conjugated double bonds

Summary It has been shown that macromolecular compounds possessing conjugated double bonds reveal new magnetic properties. In the first place, the presence of a sufficiently developed system of conjugate double bonds produces the phenomenon of unpairedness in the basic state of the system, which is manifested in pure spin paramagnetism. It may be suggested that this effect occurs for all molecules possessing conjugated double bonds, but may only be observed experimentally with the experimental techniques at present available for sufficiently large molecules. In the second place, the macromolecular systems which have been studied are characterized by properties closely similar to the antiferromagnetic properties revealed by substances with incompletely compensated antiferromagnetic interaction. This effect depends essentially on a regularized structure within the organization of all the specimens. The authors believe that further investigation involving the synthesis of polymers of this class may lead to the creation of polymeric materials with magnetic properties which, not only qualitatively but also quantitatively, will approximate to the magnetic properties of the ferrites.Translated from Zhurnal Strukturnoi Khimii, Vol. 1, No. 1, pp. 103–108, May–June, 1960     

Aggregation of paramagnetic particles in the presence of a hydrodynamic shear

We present an experimental study of the aggregation of paramagnetic particles, in the presence of controlled laminar shear flow, conducted in microchannels subjected to an external magnetic field. The microfluidic channels are made of either glass/silicon or polydimethylsiloxane. In ranges of time up to hundreds of seconds, the growth mechanism of the linear chain consists of the accumulation of isolated particles or small clusters onto existing chains, which are all moving at different speeds. In this time regime the chain length increases linearly and has a growth rate that increases as a power law with the shear. At longer times the chain lengths saturate. The Smoluchovski model, which assumes single particle-chain interactions only, closely reproduces the observations both qualitatively and quantitatively. In particular, the evolution of the growth rate of the mean chain length with respect to the shear rate S, predicted as S1/4, is found to be consistent with the experiments.     

Understanding the crystallization process of a diketopyrrolopyrrole-based conjugated polymer in blend films

The film morphology of fullerene and diketopyrrolopyrrole-based conjugated polymers (PDPPs) blends largely influences the device performance in organic solar cells. It is critical to control the morphology of blend films, which usually requires investigations of the crystallization of PDPP-based thin films. Here, we study the influence of marginal solvent additive 1,2-dichlorobenzene (ODCB) and non-solvent additive 1,8-diiodooctane (DIO) on the crystallization of poly[2,5-bis(2-octyldodecyl)pyrrolo-[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-2,2′: 5′,2″: 5″,2″′-quaterthiophene] (PDQT). The blends formed fibril structures in thin films, as revealed by transmission electron microscopy. The fibril density increased and the width decreased with the ODCB amount. The critical ODCB content to achieve constant fibril width is almost proportional to the concentration of PDQT. Higher ODCB content also results in higher fibril density in pure PDQT films. In contrast, the amount of DIO has a negligible influence on the fibril width and density of thin films. Moreover, novel dendritic fibrils were formed in PDQT films upon addition of ODCB. A model based on nucleation and growth is proposed to explain these findings. The heterogeneous nucleation was dominant with the presence of ODCB, while the homogeneous nucleation was prevailing when DIO was used. The results show that initial nucleation density and growth direction are key factors determining the fibril width.     

模型氮化物对邻二甲苯催化裂化反应的影响

在固定床微反实验装置中考察了不同模型氮化物对邻二甲苯催化裂化反应的影响,N元素的添加量为4000μg/g,催化剂的活性组分为USY分子筛。结果表明,吡啶、喹啉导致邻二甲苯的转化率有所下降。吖啶对焦炭的贡献,与其在催化剂上的吸附有关;同时吖啶诱导邻二甲苯生成更多的焦炭,并伴随氢气的大量生成,使邻二甲苯的加氢饱和反应与开环裂化反应得到促进。与空白实验相比,添加吖啶后,邻二甲苯的转化率略有上升,干气、液化气的收率显著提高。     

Effect of silver on phase separation and crystallization of niobium oxide containing glasses

Effect of silver introduction in sodium phosphate and sodium borophosphate glasses containing large amount of niobium oxide have been investigated using differential scanning calorimetry and XRD. Same sodium niobate phase in the Nb₂O₅-NaNbO₃ based solid solution have been observed following two heat treatments designed for nucleation and growth of the crystalline phase. Silver introduction in the glass composition is clearly responsible for increasing the crystallization rate. Its effect after nucleation and crystallization treatments has been shown. Phase metastable separation is occurring during heat treatment with formation of a phosphate rich and niobium rich phase. Crystallization effect on optical transparency of glasses and on Raman scattering response have been investigated.