ChemInform Abstract: Formation by Mixing of Chiral Host-Achiral Guest Inclusion Complexes in which the Guest Molecules are Arranged in a Chiral Form. Production of Optically Active Photocyclization Compounds by Irradiation of the Inclusion Complexes.

ChemInform ◽  
2010 ◽  
Vol 27 (4) ◽  
pp. no-no
Author(s):  
F. TODA ◽  
H. MIYAMOTO ◽  
K. KANEMOTO
Keyword(s):  
Inclusion Complexes ◽  
Optically Active ◽  
Guest Molecules

Crystalline inclusion complexes as media of molecular recognitions and selective reactions

2001 ◽  
Vol 73 (7) ◽  
pp. 1137-1145 ◽  
Author(s):  
Fumio Toda
Keyword(s):  
Inclusion Complexes ◽  
Chemical Reaction ◽  
Active Compound ◽  
Inclusion Complexation ◽  
Photochemical Reactions ◽  
Optically Active ◽  
Crystalline Inclusion ◽  
Guest Molecules ◽  
Water Suspension ◽  
Enantioselective Reactions

Hexaol host compounds which include guest molecules maximum in 1:6 ratio were prepared. Aromatic hexaol host, hexahydroxytriphenylene, was found to form chiral inclusion crystal by complexation with achiral guest molecules. Some interesting and important optical resolutions of rac-guests by inclusion complexation with a chiral host were described. When chemical reaction and the inclusion complexation procedures in a water suspension medium are combined, new economical and ecological method of the preparation of optically active compound can be established. When photochemical reactions are carried out in an inclusion crystal with a chiral host, enantioselective reactions occur, and optically active product can be obtained. Several successful reactions are described.

scholarly journals Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

2016 ◽  
Vol 12 ◽  
pp. 549-563 ◽  
Author(s):  
Vito Rizzi ◽  
Sergio Matera ◽  
Paola Semeraro ◽  
Paola Fini ◽  
Pinalysa Cosma
Keyword(s):  
Inclusion Complexes ◽  
Pyrimidine Ring ◽  
Protective Role ◽  
Supramolecular Structures ◽  
Water Soluble ◽  
Aqueous Environment ◽  
Spectroscopic Techniques ◽  
Guest Molecules ◽  
H Nmr ◽  
Cv Measurements

Since several years the inclusion of organic compounds (guests) within the hydrophobic cavity (host) of cyclodextrins (CDs) has been the subject of many investigations. Interestingly, the formation of inclusion complexes could affect the properties of the guest molecules and, for example, the influence of the delivery system can be a method to improve/change the photochemical behavior of the guest. In particular, very recent studies have shown the protective role of CDs preventing the degradation of the encapsulated guest. Starting from this consideration, in this work, only the structure and complexation mode of the inclusion complexes involving 4-thiothymidine (S4TdR, a known photosensitizer) and five CDs, namely 2-hydroxypropyl-α-cyclodextrin (2-HP-α-CD), 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD), 2-hydroxypropyl-γ-cyclodextrin (2-HP-γ-CD), heptakis-(2,6-di-O-methyl)-β-cyclodextrin (DIMEB CD) and heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB CD) were investigated by different spectroscopic techniques (UV–vis, FTIR–ATR, 1H NMR) and cyclic voltammetry analysis (CV). This work is necessary for a prospective research on the photoreactivity of S4TdR in aqueous environment and in the presence of CDs to prevent its degradation under irradiation. UV–vis, FTIR–ATR and CV measurements suggested the formation of supramolecular structures involving the employed CDs and mainly the pyrimidine ring of S4TdR. 1H NMR analyses confirmed such indication, unveiling the presence of inclusion complexes. The strongest and deepest interactions were suggested when TRIMEB and DIMEB CDs were studied. The S4TdR affinity towards CDs was also evaluated by using the Benesi–Hildebrand (B–H) equation at 25 °C employing CV and 1H NMR methods. The stoichiometry of the interaction was also inferred and it appears to be 1:1 for all examined CDs.

UV-vis Spectral Analysis of Inclusion Complexes between β -Cyclodextrin and Aromatic/Aliphatic Guest Molecules

2008 ◽  
Vol 5 (2) ◽  
pp. 173-176 ◽  
Author(s):  
Huiming Jiang ◽  
Yingmei Xu ◽  
Liyan Na ◽  
Rongchao Jin ◽  
Shufen Zhang
Keyword(s):  
Spectral Analysis ◽  
Inclusion Complexes ◽  
Guest Molecules ◽  
Aliphatic Guest

Synthesis and structural characteristics of lithocholate triads: steroid-type channels occupied by spacer fragments

2008 ◽  
Vol 64 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Urszula Rychlewska ◽  
Beata Warżajtis ◽  
Roman Joachimiak ◽  
Zdzisław Paryzek
Keyword(s):  
Inclusion Complexes ◽  
Terephthalic Acid ◽  
Lithocholic Acid ◽  
Structural Characteristics ◽  
Guest Molecules ◽  
Face To Face ◽  
Bifunctional Molecules ◽  
Hydrogen Bond Interactions ◽  
Crystal Density ◽  
Efficient Packing

Reported in this paper are the syntheses and X-ray investigations of C 2 symmetrical molecular A—B—A triads consisting of two steroid units (lithocholic acid or its methyl ester) joined together by linkers derived from bifunctional molecules such as terephthalic acid or N,N′-dicarboxypiperazine. Unlike their monomeric analogues, some of these compounds form inclusion complexes. All steroidal triads form crystals that are highly pseudo-centrosymmetric, in which the constituting molecules are held together either exclusively by van der Waals forces or form lattice inclusion complexes, with guest molecules hydrogen bonded to the host. The presence of carboxyl groups promotes the inclusion of pyridine molecules and the formation of the well known carboxylic acid...pyridine hydrogen bonds. Combined with pairwise face-to-face π-stacking between pyridine rings, these hydrogen-bond interactions lead to the formation of extended supramolecular tapes, analogous to polymers. The co-crystals of pyridine and a lithocholic acid triad undergo a symmetry-lowering phase transition from a P1 cell with Z = 1 to a P1 cell with Z = 2. The two structures are virtually the same, the two independent molecules in the larger cell being related by pseudo-translation. Changes in the type of spacer between two methyl lithocholate units from planar aromatic (terephthalic acid) to highly puckered aliphatic six-membered ring (N,N′-dicarboxypiperazine) bring about inclusion properties and changes in side-chain conformation in a crystal. Although the efficient packing of these highly elongated molecules is hindered, as indicated by low values of crystal density, ranging from 1.16 to 1.19 g cm−3, several very short C...O and H...H contacts are present in the crystals.

Molecular recognition of chiral porphyrins with amino acid esters

2005 ◽  
Vol 09 (01) ◽  
pp. 7-15
Author(s):  
Wen J. Ruan ◽  
Xiao J. Zhao ◽  
Hua Han ◽  
Jing Nan ◽  
Zhi A. Zhu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Electronic Effect ◽  
Association Constants ◽  
Optically Active ◽  
Amino Acid Esters ◽  
Cd Spectra ◽  
Guest Molecules ◽  
H Nmr ◽  
Tripos Force Field ◽  
Acid Esters

Association constants between α,α,α,β- ZnT (o- BocTyr ) TAPP (1), α,α,α,β- ZnT (o- BocAla )- TAPP (2), and a series of amino acid esters were determined in chloroform by means of titrations monitored by UV-vis spectra. Association constants increased in the order K( AlaOMe ) < K( ValOMe ) < K( LeuOMe ), showing the same preference for the electronic effect of bulky amino acid esters. For the guest SerOMe and ThrOMe , the association constants of two hosts showed different orders; the order of 1 is K( SerOMe ) < K( ThrOMe ), and that of 2 is the reverse. The host 2 shows a D -/ L -selectivity of 6.9 for leucine methyl ester at 293 K in CHCl 3, which is the highest enantioselectivity achieved in our study. The host-guest system was studied by 1 H NMR spectra. On association, every proton experiences a small upfield shift. The intensity of circular dichroism (CD) spectra of 1 in the presence of optically active guests were reduced as compared with that of free 1, while that of 2 with optically active guests was of the induced split type. Molecular modeling of the host-guest systems were studied by simulated annealing on the basis of the Tripos force field. The minimal energies of the complexes were calculated, and the results show that the recognition behavior of hosts 1 and 2 toward amino acid esters is very different. The change of the interaction energy of 2 with guest molecules is larger than that of 1.

scholarly journals Inclusion complexes of 2-methoxyestradiol with dimethylated and permethylated β-cyclodextrins: models for cyclodextrin–steroid interaction

2015 ◽  
Vol 11 ◽  
pp. 2616-2630 ◽  
Author(s):  
Mino R Caira ◽  
Susan A Bourne ◽  
Halima Samsodien ◽  
Vincent J Smith
Keyword(s):  
Inclusion Complexes ◽  
Anticancer Agent ◽  
Inclusion Complexation ◽  
Aqueous Solubility ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Rapid Dissolution ◽  
First Time ◽  
Secondary Side

The interaction between the potent anticancer agent 2-methoxyestradiol (2ME) and a series of cyclodextrins (CDs) was investigated in the solid state using thermal analysis and X-ray diffraction, while the possibility of enhancing its poor aqueous solubility with CDs was probed by means of equilibrium solubility and dissolution rate measurements. Single crystal X-ray diffraction studies of the inclusion complexes between 2ME and the derivatised cyclodextrins heptakis(2,6-di-O-methyl)-β-CD (DIMEB) and heptakis(2,3,6-tri-O-methyl)-β-CD (TRIMEB) revealed for the first time the nature of the encapsulation of a bioactive steroid by representative CD host molecules. Inclusion complexation invariably involves insertion of the D-ring of 2ME from the secondary side of each CD molecule, with the 17-OH group generally hydrogen bonding to a host glycosidic oxygen atom within the CD cavity, while the A-ring and part of the B-ring of 2ME protrude from the secondary side. In the case of the TRIMEB·2ME complex, there is evidence that complexation proceeds with mutual conformational adaptation of host and guest molecules. The aqueous solubility of 2ME was significantly enhanced by CDs, with DIMEB, TRIMEB, randomly methylated β-CD and hydroxypropyl-β-CD being the most effective hosts. The 2:1 host–guest β-CD inclusion complex, prepared by two methods, yielded very rapid dissolution in water at 37 °C relative to untreated 2ME, attaining complete dissolution within 15 minutes (co-precipitated complex) and 45 minutes (complex from kneading).

Sign in / Sign up

Export Citation Format

Share Document