Interactions naphthalene molecule

Figure 4.7. Possibilities for the synthesis of Vitamin K3. The small pore titaninm zeolite TS-1 cannot fit the large naphthalene molecule into its pore system, and thus is effective in this transformation. The larger titanium MTS material is capable of interacting with the molecule, and the desired transformation can take place.

All the results suggest that a unique mechanism is involved in the photocatalytic reaction of naphthalene on Ti02 particles. The details of the mechanism are not clear at the present stage. However, the interaction between the intermediate species generated from oxygen and water, which are assumed to be bound to the surface, and the naphthalene molecules adsorbed on the Ti02 surface is considered to be the key to the reaction. 

The most significant change of the SWNT Raman spectrum due to the interaction with pyrene or naphthalene was observed in the intensity of the low-frequency component of the G mode (G), which decreased by about 16, 15 and % 30 for SWNT with PI, N and P2, respectively. To estimate the intensity of all the bands in the spectra, the bands were normalized to the most intensive G+ band in each spectrum. All these changes are the spectral manifestations of the complex formation between the nanotubes and the pyrene/naphthalene molecules. However, all the observed changes of the SWNT Raman spectrum are not strong. This was not unexpected because... 

A crystalline 2 1 complex (Cl) of antimony trichloride and naphthalene was obtained from a hot petroleum ether solution on cooling. An X-ray analysis (275) revealed an interaction between the antimony atom and the arene n system. The structure consists of layers of antimony trichloride molecules alternating with layers of naphthalene molecules. The coordination sphere around the antimony atom is portrayed in Fig. 16. Two antimony-chlorine distances are equal, while the third is significantly longer. The antimony atom is 3.2 A away from the plane of the naphthalene molecule, thus indicating a weak n interaction. 

The naphthalene molecule is planar. The distance between substituents in the 1- and the 8-positions (and in the equivalent 4- and 5-positions) is shorter compared to substituents in e.g., the 1- and 2-positions. The 1-/8- and 4-/5-positions are often called the peri-positions after the Greek word peri which means near . Bulky substituents in these positions will sterically interact and cause a distortion of the molecule. For example, in the crystal structure of 1,4,5,8-tetraCN (CN-46) the chlorine atoms are positioned slightly above and under the plane of the naphthalene ring [157]. In octaCN (CN-75) the aromatic ring system is also remarkably distorted [185,186]. These distortions, as well as the unequal distribution of the u-electrons, most probably influence the physical properties and enhance the chemical as well as the metabolic reactivity of the compound. 

ZSM-11 zeolite is controlledj at least partially, by intracrystalline diffusion. Indeed, the zeolite channel diameter (5.6 A) is i aller than the critical diameter of m-xylene, mesitylene and naphthalene ( 7.4, 8.4 and 7.4 A, respectively). In the case of m-xylene and mesitylene (Fig lb) the first peak at low temperature is mostly due to the desorption of m-xylene and mesitylene adsorbed on the external surface [9], with Tm values (temperature corresponding to peak maximum of the TPD curve) similar to the Tm value for naphthalene sorbed on HZSM-11 zeolite. The second peaks are mostly due to the interaction of m-xylene and mesitylene which partially penetrated in the channels of the zeolites. The TPD of naphthalene sorbed on HZSM-11 zeolite (N1 in Fig. Ic) shows that N did not interact above 298 C, with Tm value close to 198 C. Because the zeolite channel diameter in H-ZSM-11 type zeolite is smaller than the critical size of N, the interaction is only possible with the external sites. Thus, the desorption of N would be mostly due to the N adsorbed on the external surface of the zeolite crystallites. In the case of H Y zeolite, the TPD result for naphthalene (N2 in Fig.lc) shows two peaks. The second one, at high temperatine (high Tm value), corresponds to the desorption of N sorbed in the intracrystalline voids of the large pore HY zeolite, which may easily accommodate naphthalene molecules. 

Calculations of triplet excitonic bands for a number of crystals have been performed by Sternlicht and McConnell (26) and they have shown that the resonant interaction, proper for a crystal, can substantially change the EPR spectra when molecules aggregate to a crystal. An interesting effect related to the resonant interaction has been predicted for the naphthalene crystal (26). The EPR spectra of naphthalene molecules embedded as a solid solution into a durene crystal show four lines (34). This crystal, similar to the naphthalene crystal, contains two molecules in its unit cell. Thus, inside the crystal a naphthalene molecule can have two orientations. Each of these orientations provides two lines in the EPR spectra,13 and only in such cases, when the direction of the applied magnetic field is invariant with respect to symmetry operations of the durene crystal, four EPR lines conglomerate into two lines. 

In crystals such as benzene, naphthalene, etc. having an inversion center, the operator ff nt vanishes identically, if only dipole-dipole interactions between molecules is taken into account. For further details on the operator Hjnt see Section 15.3. 

The bonding of the empty p orbital of the lithium atom to the dianion molecule is not determined solely by the symmetry of the HOMO of the dianon instead, it seems to be the result of a number of MO s of the complex. For example, at least four particular eigenfunctions involving lithium pa- -carbon pz overlap appear to be important in the naphthalene complex. These are shown at the left in Figure 34 in order of increasing stability. The top two correspond to the two HOMOs of the isolated anion and suggest that the lithium atoms should be positioned to the outside edges of the naphthalene molecule as observed. From our experience with the monoanion systems we expect that if the empty p orbital of the lithium atom were to interact with the carbon pz orbitals, it would do so in a 1-3 or 2-4 fashion—that is, across a set of three atoms. The B2g, Au, and... 

They started from the X-ray structure of thymidylate synthase (from E. coli bacteria) complexed with an inhibitor. A methyl probe was used with the GRID program to produce a contour map of strong interaction with the active site. On the computer screen, a naphthalene molecule (Structure 4.15) was bound into the active site, so that it had maximum overlap with the contours. 

The most precise measurements of the fine-structure parameters D and E have in fact been carried out using zero-field resonance. Figure 7.6 shows the three zero-field transitions in the Ti state of naphthalene molecules in a biphenyl crystal at T = 83 K. In these experiments, the absorption of the microwaves was detected as a function of their frequency [5]. The lines are inhomogeneously broadened and nevertheless only about 1 MHz wide. Owing to the small hnewidth of the zero-field resonances, the fine-structure constants can be determined with a high precision. This small inhomogeneous broadening is due to the hyperfine interaction with the nuclear spins of the protons (see e.g. [M2] and [M5]). For triplet states in zero field, the hyperfine structure vanishes to first order in perturbation theory, since the expectation value of the electronic spins vanishes in all three zero-field components (cf Sect. 7.2). The hyperfine structure of the zero-field resonances is therefore a second-order effect [5]. 

FIGURE 12.7 In view that perylene has non-interacting naphthalene subunits, it can, on this model, be viewed as two naphthalene molecules. 

Benzene is another kind of hydrocarbons, called aromatic compounds. It takes a hexagon shape, whose chemical structure resembles a unit of beehive. It is liquid at room temperature. That is, it has a sufficiently strong interaction among the molecules to be liquid, but not strong enough to be solid. When two benzene molecules are combined, a compound called naphthalene results. It is a solid with a special odor at room temperature and used as mothball. Why is naphthalene solid, whereas benzene is liquid at room temperature Think about it in terms of London force. It must be noted that the interaction between benzene molecules or naphthalene molecules is not only due to London force but also due to another kind. 

TCAQ adopt a butterfly-type structure similar to that found from experimental X-ray data for its isomer 9,10-TCAQ [31]. As stated above, the distortion from planarity is a consequence of the steric interaction between the cyano groups and the hydrogens in the peri position of the naphthalene unit. To avoid these interactions the molecule adopt the butterfly-type geometry shown in Figure 1.23. 

More recently, Kim et al. synthesized dendritic [n] pseudorotaxane based on the stable charge-transfer complex formation inside cucurbit[8]uril (CB[8j) (Fig. 17) [59]. Reaction of triply branched molecule 47 containing an electron deficient bipyridinium unit on each branch, and three equiv of CB[8] forms branched [4] pseudorotaxane 48 which has been characterized by NMR and ESI mass spectrometry. Addition of three equivalents of electron-rich dihydrox-ynaphthalene 49 produces branched [4]rotaxane 50, which is stabilized by charge-transfer interactions between the bipyridinium unit and dihydroxy-naphthalene inside CB[8]. No dethreading of CB[8] is observed in solution. Reaction of [4] pseudorotaxane 48 with three equiv of triply branched molecule 51 having an electron donor unit on one arm and CB[6] threaded on a diaminobutane unit on each of two remaining arms produced dendritic [ 10] pseudorotaxane 52 which may be considered to be a second generation dendritic pseudorotaxane. 

As an example of this nonlinear character we may consider two pairs of compounds, naphthalene versus quinoline and indole versus benzimidazole (Fig. 11.5). In both pairs of compounds the second differs from the first by a mutahon of an aromahc -CH group to an aromahc nitrogen, which introduces a strong H-bond acceptor into the molecule. In quinoline, which has no H-bond donor, the acceptor has no favorable interaction partner in the supercooled liquid or crystalline state, while it can make strong H-bonds with the solvent in water. Therefore, log Sw of quinoline is about 2 log units higher [35, 36] than that of naphthalene, i.e. the introduction of the H-bond acceptor strongly increases solubility in this... 

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