Organic Inclusion Complex Research Articles

Influence of microscopic parameters of chiral molecules on the first-order hyperpolarizability

One-electron model is chosen to analyze the second harmonic response of an organic inclusion complex – urea l-malic acid (ULMA). ULMA has broad transparent region and large nonlinear optical coefficient and damage threshold. Based on the ULMA crystal structure, the model parameters are determined using the unit cell parameters. Numerical results show that the contribution of electric-field to the first-order hyperpolarizability β is larger than that of magnetic-field but the contribution of magnetic-field is important and cannot be neglected. Modeling parameters pitch ξ and radius ρ are found to be involved in the position of peak of β. The peak position of β undergoes red-shift with increasing of ρ and blue-shift with the increasing of ξ. It suggests that the expected nonlinear optical response of a chiral molecule can be obtained through molecular modification to adjust ξ and ρ. Therefore, a chiral molecule may be a favorable host to afford organic inclusion complex with superb nonlinear optical properties.

Silver(I) Compounds Consisting of [2.2]Paracyclophane: Reversible Guest-Driven Solid-State Transformation and Incorporation Behavior

Reaction of [2.2]paracyclophane with silver(I) heptafluorobutyrate (AgC3F7CO2) has isolated three novel networks: [Ag4(pcp)(C3F7CO2)4] x pyrene (1), [Ag4(pcp)(C3F7CO2)4] x phen (phen = phenanthrene) (2), and [Ag4(pcp)(C3F7CO2)4] x fluorene (3), and an intercalation compound [Ag4(pcp)(C3F7CO2)4] x 2benzene (4). All the four complexes exhibit two-dimensional (2D) sheet structures in which AgC3F7CO2 form an infinite chain and pcp acts as linkage. 1, 2, and 3 show 2D flat sheets with cavities in which guest molecules are situated, whereas 4 exhibits 2D zigzag layers between which guest benzene molecules are intercalated. Pcp shows mu-di-eta1-eta2 coordination mode in 1, mu-tetra-eta1 coordination mode in 2 and 3, and mu-tetra-eta2 coordination mode in 4. The reversible guest exchanges were observed between complex 1, 2, or 3 and intercalation compound 4. It is unprecedented for metal-organic inclusion complexes that the guest exchange occurs where the guest is the solute molecule. Furthermore, 4 can release the guest, and the original framework was completely recovered after reincorporation of benzene. It should be noted that 4 can incorporate pyrene, phen, and fluorene to give 1, 2, and 3, respectively, after desorption.

Formation of Extended Tapes of Cyclic Water Hexamers in an Organic Molecular Crystal Host We thank Prof. J. E. Jackson (MSU) for his generous support of this study.

An icelike chair conformation is adopted by the cyclic water hexamers found in an organic inclusion complex. Self-assembly of the hexamers into one-dimensional tapes (see picture), which interact very weakly with the organic host, confers on them characteristics similar to those of liquid water, as attested by FT-IR spectroscopy.

Organic inclusion complex strategy for designing nonlinear optical crystals for ultraviolet applications

Based on Molecular Engineering and Crystal Engineering concepts, a new method for designing nonlinear optical (NLO) crystal materials, the Organic Inclusion Complex (OIC) method has been demonstrated. In defining an appropriate optical transparent range with respect to the Molecular Engineering method, small organic molecules containing n-π conjugation were selected as “second order harmonic generation (SHG)-active units”(guests). Together with the Crystal Engineering method, chiral molecules were used as “molecular scaffolding” (hosts) to combine with the “SHG-active units” by hydrogen bonds. The former can provide a nonlinear optical effect. The latter leads to the OIC with a noncentrosymmetric structure and are expected to enhance the macroscopic nonlinearity in a synergistic mode of guest and host by inducing the guest molecular dipole alignment as well as other properties, such as thermal stability, mechanical strength and ease of growth. Here, we report two new inclusion complex crystals, urea-(d)tartaric acid (UDT) and urea-(dl)tartaric acid (UDLT) (here, d means dextral and dl means racemic). UDT and UDLT crystals belong to P2,2,2, and P2, space group, respectively. Bulk size crystals with high optical quality were successfully obtained from aqueous solution by using a temperature-lowering method. The experimental results show that these two crystals demonstrate higher NLO effects and shorter wavelength cutoff.

Intercalation of Alkylammonium Cations into a Layered Titanate in the Presence of Macrocyclic Compounds

Novel one-pot synthesis of layered organoammonium−tetratitanate intercalation compounds by the ion exchange reactions between potassium tetratitanate (K2Ti4O9·nH2O) and alkylammonium chlorides in the presence of a crown ether (18-crown-6) or a cryptand ([2.2.2]-cryptand) in an organic solvent (1,4-dioxane) is reported. The intercalated alkylammonium ions take a paraffin type arrangement in the interlayer space of tetratitanate. The macrocyclic ligands preferentially interact with interlayer potassium ions to promote the ion exchange reactions. The novel one-pot synthesis of the organic−tetratitanate intercalation compounds is a versatile technique for the preparation of inorganic−organic inclusion complexes.

Characterization of linear and nonlinear optical properties of a new single crystal: Urea-(d)tartaric acid(UDT)

We describe a new method, organic inclusion complex, to design materials without center of inversion for application in quadratic nonlinear optics in the ultraviolet region. The characterization of linear and nonlinear properties of such an inclusion complex crystal, urea-(d)tartaric acid(UDT), are presented.

Stochastic fluctuations in H-bonded crystals and biological materials

Our recent results from quasielastic incoherent neutron scattering studies on the dynamics of protons in solid-state protonic conductors, on water in an organic inclusion complex and on the protein bacteriorhodopsin in purple membrane are reviewed.