Tris(5-acetyl-3-thienyl)methane Research Articles

Guest capture, storage and removal in the TATM host framework: a single-crystal study

The organic host molecule, tris(5-acetyl-3-thienyl)methane (TATM) is known to form a variety of van der Waals inclusion compounds. Surprisingly, this host framework has been shown to be stable despite near-complete guest loss. In the present study we examine the degree to which guests can be removed from the host cavities without framework collapse, as well as the ability of the depleted host framework to re-adsorb guest molecules, including adsorption of a two-component mixture of guests, all in a host system that has no channels for transport. The response of the host framework to changes in guest content is reported as well.

Structural variety in tris(5-acetyl-3-thienyl)methane (TATM) inclusion compounds

Structural variety in tris(5-acetyl-3-thienyl)methane (TATM) inclusion compounds

High‐Resolution Solid‐State NMR Studies of Inclusion Complexes

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The first example of a crystalline guest-free form of the tris(5-acetyl-3-thienyl)methane (TATM) host material

The first example of a guest-free crystalline form of tris(5-acetyl-3-thienyl)methane (TATM), in both powder and single crystal form, was obtained by leaching water-soluble guests out of the guest-host inclusion compounds with acetone, ethanol and methanol.

Polymorphism and Structure in a Pentamorphic Guest−Host Material: The Tris(5-acetyl-3-thienyl) Methane (TATM) Inclusion Compound with 1,3-Dichloropropane

In this work, we describe the preparation and structural properties of five polymorphs of the 1G:2H, 1,3-dichloropropane/tris (5-acetyl-3-thienyl) methane (TATM) inclusion compound. A number of different preparative methods were used to give products whose structures were solved by single-crystal X-ray diffraction. In addition, solid-state 13C NMR spectroscopy and powder X-ray diffraction (PXRD) were used for bulk phase identification. On the basis of the unit cell parameters determined from single crystal X-ray diffraction experiments, the PXRD results were used to resolve the products as being from either pure or mixed phases. In four of the five forms, the host TATM molecules have similar torsional conformations and share a common layered motif. The guest molecules are disordered and reside in cages or channels that are formed from the stacking of these layers. In the fifth form, the conformation of the TATM host molecules differ significantly, and the disordered guests reside in a pronounced zigzag ch...

Water and tris(5-acetyl-3-thienyl)methane (TATM) assemble into a one-dimensional channel compound.

Tris(5-acetyl-3-thienyl)methane (TATM), a well known hydrophobic host compound, assembles with water molecules into a material with one-dimensional channels that also contain water.

Polymorphism, Structure, Guest Conformation, and Dynamics in the Inclusion Compound of 1,2-Dichloroethane with Tris(5-acetyl-3-thienyl) Methane: a Combined Single Crystal and Powder X-ray Diffraction, 13C CP/MAS, and 2H NMR Study

Various physicochemical characterization techniques were used to study the structure and guest dynamics of the 1,2-dichloroethane/tris (5-acetyl-3-thienyl) methane (TATM) inclusion compound. This complex was observed to crystallize in two forms, a triclinic P-1 structure and a less usual monoclinic P21/c form. The X-ray structures indicate that the TATM molecules form “bottleneck” channels parallel to the crystallographic c axis in both forms and that the guests exist exclusively in the trans form. Solid-state deuterium NMR spectroscopy was used to study the dynamics of the 1,2-dichloroethane-d4 guest in the triclinic form. The simplest model consistent with the experimental NMR spectra was based on internal rotation about the C−C bond (a trans/gauche conformational equilibrium). As this was not consistent with the X-ray structure, another model was developed where the trans conformer performs 180° flips about an axis through the center of symmetry of the guest and perpendicular to the Cl−C−C−Cl plane. Th...

Structural Type and Thermal Stability of Tris (5-acetyl-3-thienyl) Methane Inclusion Compounds: a Combined 13C CP/MAS NMR, Powder X-Ray Diffraction and Differential Scanning Calorimetric Study

Tris (5-acetyl-3-thienyl) methane (TATM) inclusion compounds with a wide variety of guest molecules have been studied by the techniques of solid-state 13C cross polarization/magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS NMR), powder X-ray diffraction and differential scanning calorimetry (DSC). The approach taken was to study guests with the same hydrocarbon backbone but with different halogen substituents (F, Cl, Br, I) at selected sites on that backbone. From the multiplicities of the host signals in the 13C CP/MAS NMR spectra, the number of TATM molecules in the crystallographic asymmetric unit was determined. Powder X-ray diffraction experiments allowed us to investigate structural isomorphism of TATM inclusion compounds with different guests. In most cases, TATM forms isomorphic structures with guests that have the same hydrocarbon backbone, but with different halogen substituents. This was illustrated in the case of cyclohexyl halide and methylene halide guests. On the other hand, TATM will form one type of structure with a guest that has smaller halogen substituents (e.g., F, Cl, Br), but a completely different structure with a guest that has larger halogen substituents (e.g., I). This was illustrated in the case of monohalobenzene, 2-halobutane and 1,3-dihalopropane guests. Differential scanning calorimetry experiments allow one to investigate thermal stabilities of inclusion compounds with different guests. The enthalpy of decomposition data show that TATM forms more stable inclusion compounds with guests that have smaller, more electronegative halogen substituents (for a given hydrocarbon backbone), and the stability decreases as the size of the halogen substituent increases.

Conformational Isomerism of the Host as a Factor in Molecular Recognition in Host–Guest Inclusion Complexes: Example of Tris(5-acetyl-3-thienyl)methane

The tripod molecule tris(5-acetyl-3-thienyl)methane (TATM) is a flexile molecule, i.e. one that can occur in many conformationally isomeric states (conformers), which forms host–guest inclusion complexes with a large variety of guests (solvents). Some 40-odd different types of guest have been reported to form inclusion complexes. Five different types of crystal structure (all racemic), with nine different guests, have been reported in the literature and structural information is available for 17 crystallographically independent TATM molecules; most of the guests are disordered. Our analysis of this (substantial but, nevertheless, incomplete) database shows that each group of crystallographically isomorphous structures contains a particular TATM conformer with characteristic torsion angles about the bonds between methane carbon and the three thienyl rings (τ1, τ2 and τ3); the range of torsion angles in a particular structural group does not exceed 10°. Conformers are in addition distinguished via the stereochemistry of the acetyl group; there are approximately equal numbers of examples with carbonyl oxygen syn or anti to ring sulfur, intermediate conformations not being found. So far three different types of conformer have been encountered for the TATM molecule considered as an entity. A necessary condition for the occurrence of a particular conformer type is that the torsion angles τ1, τ2 and τ3 are such that ring H atoms should not approach more closely than (say) 2.4 Å, but this is not sufficient as considerably larger distances are found in some conformer types. Crystallization of the inclusion complex from a particular solvent can be envisaged to occur as follows. The TATM solution will contain a Boltzmann distribution of host conformers, the distribution depending on temperature but not on the nature of the solvent. Under suitable temperature and solubility conditions, the solvent will crystallize together with the appropriate conformer to form the inclusion complex-nuclei formed at this recognition stage, then grow into crystallites of the inclusion complex. The perturbed Boltzmann distribution (depleted in appropriate conformer) will continuously revert to its equilibrium form by conversion of the non-appropriate into the appropriate conformer as the crystallization proceeds.

A deuterium NMR study of guest molecular dynamics in tris(5-acetyl-3-thienyl) methane inclusion compounds

Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T1) are used to investigate the guest molecular dynamics of tris(5-acetyl-3-thienyl) methane (TATM) inclusion compounds. The seven guests: acetonitrile, nitromethane, dimethyl sulfoxide, benzene, mesitylene, ortho-xylene, and para-xylene show a wide variety of motional behaviour. The reorientation of acetonitrile in TATM and nitromethane in TATM were both modelled as precession on a cone, the base of which is more elliptical in shape for nitromethane, as would be expected considering their molecular symmetries. DMSO in TATM does not undergo any reorientation other than methyl rotation at the temperatures investigated. At low temperatures, the 2H lineshape and the deuterium spin-lattice relaxation time both depend on the rate of methyl rotation. Activation barriers of 11.7 (±0.4) kJ/mol and 11.2 (±0.5) kJ/mol were found from the two techniques, respectively. Benzene undergoes sixfold reorientation about the principal molecular axis; however, the rate is still greater than 108 Hz down to 113 K. The spin-lattice relaxation time profile does not reach a minimum on decreasing temperature to 112 K, while the slope of this plot provides an activation energy of 4.1 (±0.4) kJ/mol for the sixfold reorientation. The deuterium NMR spectra of mesitylene-d9 in TATM can be simulated using a model where the guest occupies two different sites in the TATM lattice, with the guest molecules performing in-plane C3 rotation either very rapidly (k > 108 Hz) or very slowly (k < 103 Hz), with the relative populations of each changing with temperature. Another model proposed suggests the possibility that there is a continuous distribution of motional rates, the median of which is increasing with temperature. This second model is more realistic; however, too many parameters are present to consider a detailed fit. Finally, both o-xylene and p-xylene are rigidly held in the TATM clathrate, while rotation of the methyl groups is rapid. Key words: inclusion compounds, solid state deuterium NMR spectroscopy, molecular dynamics.

A deuterium NMR study of guest molecular dynamics of acetone in two organic inclusion compounds

Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T1) are used to investigate the dynamics of the guest molecule, acetone, in tris(5-acetyl-3-thienyl)methane (TATM) and cyclotriveratrylene (CTV) inclusion compounds. 13C CPMAS powder NMR spectra were obtained for each clathrate, to verify inclusion. In acetone: TATM, the guest molecule is undergoing twofold reorientation about the CO bond, exchanging the two methyl groups. An activation energy of 20 (± 1.4) kJ/mol, for the two-site jump motion, was found, independently, from deuterium NMR spectra an T1 measurements. Acetone in CTV performs the same type of motion as acetone in TATM. Activation energies of 25.0 (± 3.2) kJ/mol and 24.1 (± 0.5) kJ/mol were determined using the same two techniques. both inclusion compounds, the rate of methyl rotation within the acetone molecule is greater than 108 Hz even at the lowest temperature measured (84 K). Analytical expressions for the spin-lattice relaxation time (T1), for a twofold jump, were derived. Calculated values of the effective quadrupolar coupling constant and T1min for the guests agree very well with the experimental data. The 84 K spectrum of acetone:TATM unexpectedly shows some asymmetry, the origin of which is discussed. Finally, these two clathrates are compared to the recently examined acetone: tri-ortho-thymotide inclusion compound. Key words: inclusion compounds, deuterium NMR, solid state NMR spectroscopy, molecular dynamics.

Tris(5-acetyl-3-thienyl)methane–cyclononanone (1/1) inclusion compound

Tris(5-acetyl-3-thienyl)methane (TATM) forms an inclusion compound with cyclononanone in a host/guest ratio of 1/1, C 19 H 16 O 3 S 3 .C 9 H 16 O. The crystal belongs to the monoclinic system. The cavity formed by the TATM molecule is of a zigzag-channel type, parallel to the c axis. The cyclononanone guest molecule accupies two orientationally disordered positions with occupation factors of 25 and 75%. The two cyclononanone molecules each have the (g - g - ggg - g - sg - s) conformation

Structural and conformational analysis of six-, seven-, and eight-membered cycloalkanes in tris(5-acetyl-3-thienyl)methane inclusion compounds

Tris(5-acetyl-3-thienyl)methane (TATM) forms inclusion compounds with cyclohexane, -heptane, and -octane in a host/guest ratio of 2:1. The clathrate compounds have been studied by X-ray crystallography. The inclusion compound with cyclohexane crystallizes in two distinct triclinic unit cells of space group [Formula: see text] in the A form, the unit cell dimensions are a = 8.622(2), b = 10.194(2),c = 12.795(2) Å, α = 79.09(1)°, β = 72.74(1)°,γ = 84.89(1)°, V = 1053.9(4) Å3(220 K); for the B form, a = 11.668(4), b = 13.729(3), c = 14.227(4) Å, α = 89.40(3)°, β = 77.20(4)°, γ = 76.24(4)°, V = 2157(1) Å (room temperature). In the A form the cavity is of the channel type but the guest molecule is located on a centre of inversion while in the B form the cavity is also of the channel type but the guest molecule is in a general position. The inclusion compounds of cycloheptane and cyclooctane crystallize only in the B form. The guest molecules in the B form are disordered. Conformational analyses of the guest molecules have also been performed by a combination of molecular dynamics and energy minimization.