Andreas Wierig

Inclusion Compounds of Diol Hosts Featuring Two 9-Hydroxy-9-fluorenyl or Analogous Groups Attached to Linear Spacer Units

A series of new clathrate host molecules 1−15, each containing two 9-hydroxy-9-fluorenyl or analogous terminal groups attached to linear central units of different lengths and structural compositions, has been synthesized. Their crystalline inclusion compounds with a variety of organic guests − including amines, alcohols, ketones, and other dipolar aprotic compounds or aromatic hydrocarbons − are reported (229 examples of clathrates) and their properties are compared. The crystal structures of a free host compound and of six selected clathrates of different compound classes have been determined by X-ray diffraction, showing varied modes of supramolecular interaction.

Inclusion of organic vapours by crystalline hosts. Chemical-sensitive coatings for sensor applications

Abstract Solid inclusion hosts, such as derivatives of bis-fluorenyl (1, 2) and maleic acid (3), can include organic solvent vapour molecules such as acetone, cyclohexanone, methanol, ethanol, 1-butanol and dioxane to form stoichiometric inclusion complexes. Due to their ability to be used as gas-sensing layers, the absorption and desorption of acetone by crystalline host 1 is on-line monitored by a recording balance. For sensitivity improvement hosts 1 and 3 are coated onto the surface of a quartz crystal, the indicating device of the quartz microbalance. In the presence of various saturated vapour atmospheres we obtained reversible and reproducible signals within a short response time. Stoichiometrics of sorptive clathrate formations with 1–3 are determined by weighing. By differential scanning calorimetry (DSC) temperature dependence and enthalpies of guest desorption from host 1 can be determined, thus indicating weak host-guest interactions.

Chemical sensor materials based on clathrates

The solid host compound 2,2′-bis (9-hydroxy-9-fluorenyl)biphenyl 1 enclathrates organic solvent vapours such as acetone, methanol and 1-butanol to give stoichiometric inclusion complexes. Using differential scanning calorimetry (DSC), desorption enthalpies were estimated to 10–20 kJ/mol, indicating weak host-guest interactions. Clathrate formations with acetone and methanol are reversible and reproducible, and show a dependence of the mass increase on the solvent concentration in a gas flow. The application of host compound 1 as receptor layer can be important for the future development of mass sensors for the determination of organic solvent vapours.

Separation of Lutidine Isomers by Inclusion

Structures of the inclusion compounds formed between the host compound 1,4-bis(9-hydroxy-9-fluorenyl)benzene and three lutidine regioisomers, 2,4-, 3,5-, and 2,6-lutidine, have been elucidated. Competition experiments were performed to investigate the degree of host selectivity for complexation with the lutidine isomers. Lattice energy calculations explain the results of the competition experiments, and thermal analysis shows that the desolvation reactions are complex.

Clathrates as coating materials for dielectric transducers with regard to organic solvent vapour sensors

Abstract The interdigitated capacitor using 2,2′-bis(9-hydroxy-9-fluorenyl)biphenyl ( 1 as inclusion host, embedded in a polymer matrix (polyvinyl chloride with a plasticizer) as coating material, shows a sensitivity to organic solvent vapours. The sensitivity depends on the host compound contents in the membrane. The bset results have been obtained for the PVC membrane containing 27% 1 and 57% 2-fluorophenyl 2-nitrophenyl ether as plasticizer. The sensor demonstrates reproducible, reversible responses with a response time of 1–2 min when exposed to vapours of dichloromethane and tetrachloroethylene with concentrations in the range 0.05–3.5 vol.%, while being about 10 times more sensitive to tetrachloroethylene.

Complexation with diol host compounds. Part 20. Kinetics of desolvation of inclusion compounds of 2,2′-bis(2,7-dichloro-9-hydroxy-9-fluorenyl)biphenyl with 1,4-dioxane and 1,3-dioxolane

The structures of the inclusion compounds of 2,2′-bis(2,7-dichloro-9-hydroxy-9-fluorenyl)biphenyl with 1,4-dioxane and 1,3-dioxolane, with host : guest ratios of 1: 3.5 and 1: 2 respectively, have been elucidated. Their kinetics of desolvation have been studied and the dioxane inclusion compound desolvates in two distinct steps, each following the first-order kinetic model. The dioxolane inclusion compound desolvates in one step and follows a contracting area model. X-Ray powder photography shows that the dioxane inclusion compound forms a stable intermediate γ-phase before final desolvation to a non-porous α-phase.

Triarylmethanol Host Compounds. Synthesis, Crystalline Complex Formation and X-Ray Crystal Structures of Three Inclusion Species

A variety of triarylmethanol compounds including benzo condensed and laterally substituted derivatives 1–10 have been prepared and shown to act as crystallinehosts for the inclusion of organic solvents involving protic polar, aprotic dipolar and apolar molecules. The inclusion ability is ratherhigh for aprotic dipolar solvents while protic polarcompounds are only rarely enclathrated. Host 9 is an exception, being also efficient with alcohols and amines. Compound3 displays no inclusion formation under theexperimental conditions. X-ray crystal structures of the inclusion compound 1⋅acetone (2:1) and of two amineinclusion compounds of host 9 [9⋅ n-propylamine(1:1), 9⋅di-n-propylamine (1:1)] are reported showing the formation of H-bondedhost-guest associates as the common feature of supramolecular association.Supplementary data relating to this article have beendeposited with the British Library, No. SUP 82226 (10 pages).at Boston Spa, Wetherby, West Yorkshire, U.K., as Supplementary Publication.

Complexation with diol host compounds. Part 10. Synthesis and solid state inclusion properties of bis(diarylhydroxymethyl)-substituted benzenes and biphenyls; X-ray crystal structures of two host polymorphs and of a non-functional host analogue

A new family of host molecules where the molecular axis of usual ‘wheel-and-axle’ compounds is replaced by aromatic units is described. These diol hosts form crystalline inclusions with a variety of uncharged organic molecules mainly of a polar nature (53 different copecies). The formation and stoichimetry depend in a systematic manner on structural parameters of the host allowing these hosts to be more selective than the parent compounds. Non-hydroxylic analogues do not function as host molecules. The crystal structures of two polymorphs of host compound 2 and of the inefficient compound 9 have been studied. Crystal data: 2(polymorph α1), monoclinic, C2/c, a= 16.827(2), b= 15.212(3), c= 10.708 A, β= 97.01(1)°, V= 2721 A3, Z= 4; 2(polymorph α2), triclinic, P, a= 8.807(2), b= 10.687(6), c= 16.263(3)A, α= 100.97(3)°, β= 91.47(2)°, γ= 113.02(3)°, V= 1375 A3, Z= 2; 9, monoclinic, P21/n, a= 12.781(3), b= 7.773(2), c= 28.405(17)A, β= 103.01°, V= 2749 A3, Z= 4. Alignment of the axis of the molecular backbones was observed in all structures. Formation of host-host hydrogen bonds in the case of the α2-polymorph of 2 resulted in a gauche conformation of the hydroxy moieties unlike the α1-polymorph of 2 which is anti. The packing factors are 17.00, 17.18 and 18.09 A3 per non-hydrogen atom for 2(α1), 2(α2) and 9, respectively.

Complexation with diol host compounds. Part 17. Structures and thermal analysis of 9,9′-dihydroxy-9,9′-bifluorene with ethanol, 1-butanol and pyridine

Abstract Structures of the inclusion compound 9,9′-dihydroxy-9,9′-bifluorene with ethanol, 1-butanol and pyridine have been determined. The structures are stabilised by networks of hydrogen bonds. The thermal analysis indicates a single step decomposition process with concomitant phase transition of the structures. Accurate vapour pressure measurements at various temperatures yield the enthalpy change for the guest release reaction.

Complexation with diol host compounds. Part 24. Kineticsof desolvation of inclusion compounds of 2,7-substituted2,2′-bis(9-hydroxy-9-fluorenyl)biphenyl hosts with acetone

The structures of the acetone inclusion compounds of 2,2′-bis(2,7-dichloro-9-hydroxy-9-fluorenyl)biphenyl (compound 1) and 2,2′-bis(2,7-di-tert-butyl-9-hydroxy-9-fluorenyl)biphenyl (compound 2), with host∶guest ratios of 1∶2 and 1∶1, respectively, have been elucidated. Compound 2 desolvates at 175 °C, whereas compound 1 is much less stable and desolvates at 80 °C. Compound 1 desolvates in a single deceleratory step following a three dimensional diffusion kinetic model. The desolvation of compound 2 follows the first-order kinetic model. The activation energies of desolvation have been evaluated.