Bis-phenol Bis-schiff Base Compounds And Their Intermolecular Non-Covalent Interactions

Due to the non-covalent synthesis, such as hydrogen-bond Van der Waals force has been a topic of vital scientific research of organic frameworks,liquid crystalline and self-assembly technique. In this thesis, a variety of bi-phenol-bi-schiff base molecule were synthesized with 3,4–dihydroxyben zaldehyde,P-phenylenediamine and N-bromide. The designed moleculars have simple structure, and all of them contain hydrogen on the para-popsition as the proton donor and enhance the combination with neighbor moleculars. Meanwhile, there is–C=N- in the schiff base, which has nitrogen atoms on the para-position and it can act the proton acceptor and provide the rigid framework of the molecular. On the basis of the above discussion, it is easy to form organic frameworks with this kind of moleculars based on the hydrogen-bond, and make it possible to form organic nanocrystal and increase the ratio of the length and the diameter of the molecular easily to study the property of liquid crystalline. The main works are as follow:1,We controled the reaction position with bromide by adjusting the solution of the PH value of 3,4–dihydroxybenzaldehyde, using his four-alkoxy replace product to react with the Phenylenediamine. According to the different number of carbon in n-bromide, a series of bis- phenol-bis-schiff base have been synthesized with n = 1,4,8,12,16 and used nuclear magnetic resonance and elemental analysis method to characterize. 2,We use the method of volatile solvents, used tetrahydrofuran as a solvent, petroleum ether as the proliferation, choosing different time for crystal growth, and obtained three crystal structure of p-OR1-BPBS. According to Crystal data analysis, we found that, when the crystal growth for 5 days, quadrilateral network crystal structure A has been obtained with the main driving force of hydrogen bonds, supplemented by other weak interaction. When the crystal growth time is about one and a half months, the crystal structure is very different with the former. In the crystal structure, another lateral hydroxyl molecules -C = N-group beyond the effective range of hydrogen bonds, thus a fish bone-shaped one-dimensional crystal structure of B formed, relying on the weak molecular interactions between the molecules, and with the elements in the cell more closely,stability. In addition, we added a certain amount of 4,4 'bipyridine molecules, provided hydrogen bonds to the moleculars, making the lateral phenolic hydroxyl with 4,4' bipyridine ends of the nitrogen atoms formed Molecular hydrogen bonds, staggered with the layered and formed a fish bone-like one-dimensional network structure C. It is worth noting that, although the crystal structure of the A and C exist in hydrogen bonds, we can see that the hydrogen bonds in the crystal C stronger than these in crystal A. We believe that p-OR1-BPBS bipyridine and the nitrogen atoms easily form strong hydrogen bonding, and this is a stronger force than p-OR1-BPBS molecules themselves, which interfered the p-OR-BPBS form the network structure by themselves with the assembly process, but only with the common bipyridine molecules formed another one-dimensional network structure. Compared Crystal B with C, although from the network accumulating the single-crystal structure, the two are similarwith the layer and layer between the interlock. However, there is a strong hydrogen bond in the single crystal C, and only weak interaction in the crystal B. Also from the cell size, crystal C is smaller than single crystal B, which can also speculate the same conclusion. This point can also determine the interaction between bipyridine and p-OR1-BPBS stronger than p-OR1-BPBS itself. Therefore, we can change the conditions of crystal growth to get the structure we need.3,We used DSC-(DSC), polarized light microscopy (POM), variable temperature XRD and Fourier transform infrared spectroscopy methods to study n = 4,8,12,16 p-ORn-BPBS .We found that, when n=4, and found no obvious nature of the liquid crystal, by calculation indicates that this is because of the aspect ratio of less than 4 caused by, and when the tail linked to the length up to 8, with the molecules on the liquid crystal and significant. DSC curves of their have multiple endothermic / exothermic peak, and in polarized light microscopy, it can be observed under a variety of liquid crystal texture. To n = 8 as an example, in the process of cooling down, DSC curve followed by four exothermic peak, and polarizing microscope show the three liquid crystal texture, respectively SmA *, SmC *, SmB *. XRD through variable temperature zone in a small corner of the characteristics of a sharp peak, you can speculate the molecules on the state of liquid crystal is layered arrangement, by calculating the length of the pitch and the molecules that we know of is 63.27 degrees in the listing with layer. In the infrared spectra, we can observe -CH2 group stretching and non-stretching peak. Its strength and direction of movement, such as analysis, indicates that with the increase of link, the end of strand conformation gradually changed in an orderly manner. With the infrared data on the further analysis, we know, the tail number of carbon atoms linked to 12, the end of molecules close to to zig-zag the conformation. And to the presence of such a conformation, it conducive to the formation of SmC *, this also explains why the range of temperature with SmC * is wider and more stable .This differential scanning calorimetry (DSC) and polarized light microscopy (POM) to the SmC * measured the same results.4,We choose from a variety of long chain p-OR-BPBS for structural elements, organic nanoparticles assembly Preparation and study to understand organic material in mesoscopic size (nano-/micro-/mesoscales-) of the internal structure. Through the use of reprecipitation, nanoparticles were prepared in a distributed system and the UV-Vis spectrum and morphology changes with time were studied. From the UV-Vis spectrum, we find that molecules in the process of gathering are gathered in the form of J-tpye, and with the circles of gathering,dissolved,gathering again , size of nanoparticles are increasing and the shape is changed . N = 8 to as an example, from the field emission scanning electron microscopy (FESEM) picture, we can clearly observed that the size of spherical nanoparticles with the 30 nm diameter circle around is increased with time of long gathered to around a length of 5um Rod structure. In addition, under the CH2Cl2 steam-induced conditions, the morphology of p-ORn-BPBS nanoparticles have taken place in the change from the original spherical particles larger circle even band structure, was induced to become 20 nm in diameter around the ball. Therefore, we can control the growth of time and changes in growth conditions, to adjust the shape and size of nanoparticles.