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Diastereotopic groups also arise in achiral molecules. For instance, any one pair of CH 2 hydrogens in 3-pentanol (Figure 1) are diastereotopic, as the two CH 2 carbons are enantiotopic. Substitution of any one of the four CH 2 hydrogens creates two chiral centers at once, and the two possible hydrogen substitution products at any one CH 2 ...
The three kinds of CDs, α-CD (6 units), β-CD (7 units), and γ-CD (8 units) differ in their cavity sizes: 5, 6, and 8 Å, respectively. α-CD can thread onto one PEG chain, while γ-CD can thread onto 2 PEG chains. β-CD can bind with thiophene-based molecule. [5] Cyclodextrins are well established hosts for the formation of inclusion compounds.
The first description of cooperative binding to a multi-site protein was developed by A.V. Hill. [4] Drawing on observations of oxygen binding to hemoglobin and the idea that cooperativity arose from the aggregation of hemoglobin molecules, each one binding one oxygen molecule, Hill suggested a phenomenological equation that has since been named after him:
The definitions of hydrogen bond donors and acceptors used to apply Lipinski's Rule of Five [6] are easily coded in SMARTS. Donors are defined as nitrogen or oxygen atoms that have at least one directly bonded hydrogen atom: [N,n,O;!H0] or [#7,#8;!H0] (aromatic oxygen cannot have a bonded hydrogen) Acceptors are defined as nitrogen or oxygen:
Molecular binding is an attractive interaction between two molecules that results in a stable association in which the molecules are in close proximity to each other. It is formed when atoms or molecules bind together by sharing of electrons. It often, but not always, involves some chemical bonding.
Molecules based around main group elements should satisfy the octet rule when all bonding and nonbonding molecular orbitals (MOs) are filled and all antibonding MOs are empty. For example, methane is a simple molecule from which to form a main group fragment. The removal of a hydrogen atom from methane generates a methyl radical.
An additional type of bond is a "non-bond", indicated with ., to indicate that two parts are not bonded together. For example, aqueous sodium chloride may be written as [Na+].[Cl-] to show the dissociation. An aromatic "one and a half" bond may be indicated with :; see § Aromaticity below.
These variants with larger apertures are capable to included larger, different sized molecules. Based on the charge-transfer complexation of CBPQT4 + many supramolecular structures have been created, including fibrillar gels, micelles, vesicles, nanotubes, foldamers and liquid crystalline phases. In analogy to biological systems, which are ...