INCLUSION COMPLEXATION OF CYCLOBIS(PARAQUAT-p-PHENYLENE) AND RELATED CYCLOPHANE DERIVATIVES WITH SUBSTITUTED AROMATICS: COOPERATIVE NON-COVALENT CAVITY AND EXTERNAL INTERACTIONS

Abstract

The cooperative nature of non-covalent interactions which give rise to inclusion complexes involving cyclobis(paraquatp-phenylene), 1 4+ , and related cyclophane derivatives, 2 4+ -4 4+ , with substituted 1,4-phenyl and 4,4Ј-biphenyl guests has been studied by spectroscopic techniques and ab initio and semiempirical molecular orbital methods. Inclusion complex formation and stability are primarily determined by the combination of two main interaction modes involving aromatic stacking of the guest within the cyclophane cavity and external interactions between guest side arms and the exterior of the cyclophane. A balance between cavity and external forces results in supramolecular association and is shown to change depending upon the functionality and substitution of the guest. Cavity binding was probed using 1,4-phenyl and 4,4Ј-biphenyl guests, where for the 1,4-phenyl guests the primary basis for energy stabilization with 1 4+ is found to be short-range stabilizing electrostatic forces complemented by small amounts of polarizability and charge-transfer. JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, VOL. 10, 369-382 (1997) © 1997 by John Wiley & Sons, Ltd.CCC 0894-3230/97/050369-14 $17.50 many rotaxanes, catenanes and other switchable molecules, but because the intermolecular interactions involved, such as electrostatics, polarizability and charge-transfer, are ubiquitous in supramolecular chemistry. The information reported on the specific interactions involving the 1 4+ -4 4+ molecular receptors with substituted aromatic guests can also be extended by analogy to many systems of broad interest.

Diagnosis of gastrointestinal tract lesions by endoscopic ultrasound-guided fine-needle aspiration biopsy

“…A few theoretical studies have been published of host–guest complexes at the molecular mechanics 10, 11 or semiempirical levels 12–14. In a limited number of studies paraquat‐containing complexes were treated at the Hartree‐Fock or DFT (Density Functional Theory) levels 12–18. However, in many cases these methods are not adequate to correctly describe intermolecular interactions.…”

Molecular Shuttles. A Computational Study (MM and MD) on the Translational Isomerism in Some [2]Rotaxanes

“…Computational methods can be a very useful tool for modeling molecular machines and molecular devices. In fact, articles exist in the literature that study the complexation of cyclobis(paraquat- p -phenylene), 5 , with different substrates, mainly through ab initio or semiempirical calculations. − Molecular mechanics (MM) calculations readily allow energy minimizations and searching through large configurational spaces. The knowledge obtained from these theoretical studies can be useful in molecular nanotechnology to design and fabricate more powerful and useful molecular devices. , In this paper, molecular mechanics calculations have been applied to model the switching processes observed in [2]rotaxanes 1 − 4 (Scheme ) where 5 is used as macrocycle .…”

Ion Recognition Approach to Volume Reduction of Alkaline Tank Waste by Separation and Recycle of Sodium Hydroxide and Sodium Nitrate

“…Thus, compounds 12-14 contain one or more 2,6-pyridiyl moieties in addition to the 4-oxahexacyclo[5.4.1-.0 2,6 .0 3,10 .0 5,9 .0 8,11 ]dodecane cage. 36 Another series of novel host molecules, 15-20, is comprised of cage-functionalized diaza (17-crown) ethers. 32c,33a,33b Finally, two additional cage-functionalized host systems, 21 37 and 22, 38 have been synthesized.…”