Small organic molecules

K, V N Viswanadhan and J J Wendoloski 1998. Prediction of Hydrophobic (Lipophilic) lerties of Small Organic Molecules Using Fragmental Methods An Analysis of ALOGP and GP Methods. Journal of Physical Chemistry 102 3762-3772. 

The Gl method is seldom used since G2 yields an improved accuracy of results. G2 has proven to be a very accurate way to model small organic molecules, but gives poor accuracy when applied to chlorofiuorocarbons. At... 

The simplest empirical calculations use a group additivity method. These calculations can be performed very quickly on small desktop computers. They are most accurate for a small organic molecule with common functional groups. The prediction is only as good as the aspects of molecular structure being par-... 

Correlated calculations, such as configuration interaction, DFT, MPn, and coupled cluster calculations, can be used to model small organic molecules with high-end workstations or supercomputers. These are some of the most accurate calculations done routinely. Correlation is not usually required for qualitative or even quantitative results for organic molecules. It is needed to obtain high-accuracy quantitative results. 

Organic molecule calculations can be done routinely to good accuracy on workstation-class hardware. It is advisable to examine tabulations of results in order to choose a method with acceptable accuracy and computational time for the property of interest. The trend toward having microcomputer versions of computational chemistry codes is making calculations on small organic molecules even more readily accessible. 

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

F. Balkenhohl, C. Vondembusschehunnefeld, A. Lansky and C. Zechel, Combinatorial Synthesis of Small Organic Molecules, Angew Chem, Int Ed Engl 35 2289-2337 1996. 

Empirical energy functions can fulfill the demands required by computational studies of biochemical and biophysical systems. The mathematical equations in empirical energy functions include relatively simple terms to describe the physical interactions that dictate the structure and dynamic properties of biological molecules. In addition, empirical force fields use atomistic models, in which atoms are the smallest particles in the system rather than the electrons and nuclei used in quantum mechanics. These two simplifications allow for the computational speed required to perform the required number of energy calculations on biomolecules in their environments to be attained, and, more important, via the use of properly optimized parameters in the mathematical models the required chemical accuracy can be achieved. The use of empirical energy functions was initially applied to small organic molecules, where it was referred to as molecular mechanics [4], and more recently to biological systems [2,3]. 

This is an extension of MM2, and it was designed primarily for small organic molecules. It uses a cubic stretching potential... 

Chemically, plant essential oils consist largely of mixtures of compounds known as terpenoids —small organic molecules with an immense diversity of structure. More than 35,000 different terpenoids are known. Some are open-chain molecules, and others contain rings some are hydrocarbons, and others contain oxygen. Hydrocarbon terpenoids, in particular, are known as terpenes, and all contain double bonds. For example ... 

In addition to their protein part, most enzymes also contain a small nonprotein part called a cofactor. A cofactor can be either an inorganic ion, such as Zn2+, or a small organic molecule, called a coenzyme. A coenzyme is not a catalyst but is a reactant that undergoes chemical change during the reaction and... 

Coenzyme (Section 26.10) A small organic molecule that acts as a cofactor. 

Plasticizer (Section 31.5) A small organic molecule added to polymers to act as a lubricant between polymer chains. 

Vitamin (Section 26.10) A small organic molecule that must be obtained in the diet and is required in trace amounts for proper growth and function. 

Polymer LEDs are similar to thin film organic molecular LEDs first reported in 1987 17). Organic molecular LEDs utilize thin films of small organic molecules rather than polymer films as the light-emitting layer. The films of small organic molecules are undoped and have electronic properties comparable to the polymer films used in polymer LEDs. In general, the device physics of polymer LEDs is... 

Many platinum(IV) alkyls undergo this process on heating to 150-180°C, with the elimination of a small organic molecule and formation of a platinum(II) product [198, 199],... 

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