Chemical isomers are polyatomic ions or molecules that have the same formulas but different structures. There are structural isomers and stereoisomers. Although the chemical composition of the isomers is the same, their physical, chemical properties or toxicity are very different due to their different chemical structures (the way the atoms are arranged in space). Chemical isomers calculation plays a central role in drug discovery. Especially, the thalidomide event attracted chemists' attention to optical isomers because the active ingredient was (R)-thalidomide, whereas (S)-thalidomide caused teratogenicity.
Structural isomerism (also called constitutional isomerism) describes that atoms and functional groups are linked together in distinct ways with different IUPAC names. Our structural isomers calculation methods include carbon chain isomers calculation, position isomers (substitution isomers) calculation, and functional group isomers calculation. At Alfa Chemistry, we firstly identify the structure of different organic substances (alkanes, etc.), and then determine how many kinds of structural isomers each organic substance can has, and finally we can calculate the ratio between the different isomers. In addition, the structural isomerism of nanocluster is attractive and challenging, and we have the ability to solve the difficulty and provide accurate calculations.
Stereoisomerism (also called spatial isomerism) refers to chemical compounds with the same connected order of atoms or groups but in different spatial arrangements. It can be divided into configurational isomerism (including cis-trans isomerism, enantiomerism, and diastereoisomerism) and conformational isomerism. Stereoisomers caused by bond lengths, bond angles, double bonds in the molecule, rings, etc. are called configuration isomers. Stereoisomers caused only by the rotation of a single bond are called conformational isomers. Unlike structural isomers, the physical and chemical properties of various stereoisomers are relatively close. Our teams can perform cis-trans isomers calculation, enantiomers calculation, diastereoisomers calculation and conformational isomers calculation, aiming to investigate the chemical reactions mechanism and molecular properties.
Stereoisomers calculation plays a key role in the determination of natural products, asymmetric reactions, drug discovery, and drug properties. Among them, enantiomers calculation is popular with drug research due to its unique properties. More and more pharmaceutical companies have provided isomers calculation services in drug research. Moreover, optical isomerism analysis is becoming another hot spot. The number of optically active and inactive (meso) stereoisomers in an acyclic system can be calculated from the number of chiral centers present in the molecule.
Recently, scientists analyze the influence of the molecular structure of different isomers on their functions and screen small molecule drugs targeting these isomers. And the standard workflow is as follows:
1. Create a preliminary molecular structure.
2. Set parameters and build molecular models to obtain a variety of isomer.
3. Use molecular force fields methods to optimize the searched structure.
4. Further accurately screen the molecular structure through Discrete Fourier Transformation.
(Asymmetric) organic catalysis raises the molecular structure to a whole new level. It not only makes synthetic chemistry more environmentally friendly, but also makes it easier to produce asymmetric molecules. Multiple enantiomers are synthesized to be applied in (asymmetric) organic catalysis. The catalytic reaction has excellent stereoselectivity with the application of chemical Isomers, and the selectivity of optimal diastereoisomer is greater than 99%. In addition, the (asymmetric) catalytic reactions has been proven efficient, stable and repeatable.
For chiral drugs, chiral chromatography, high-performance capillary electrophoresis and other stereoselective methods are widely applied for the detection of stereoisomeric impurities. In addition, optical purity inspection methods are used for the impurity detection of racemate drugs. The resolution between each impurity and each stereoisomer peak should be investigated to determine whether it meets the requirements or not. Acid, alkali, light, heat, oxidation and other moderate damage tests are important indicators to verify whether the method can avoid the interference of degradation products on the detection of enantiomers.
With the rapid development of separation technology, the research on active resolution of isomers with multiple chiral carbon atoms has become more and more common. Nowadays, isomers are widely present in the molecules of existing chiral pesticide compounds. The S configuration isomers have been successfully separated from commercial pesticide varieties. The experiments show that the structure of the S configuration isomer is more stable, and the herbicidal activity is even 1,000 times that of the R configuration isomer. This discovery belongs to the application of the resolution of racemates in agrochemical research. The results show that S configuration isomer has higher herbicidal activity through chiral resolution and herbicidal activity screening.
We select the calculation method based on the first principles to calculate chemical isomers. Combined with the CASTEP total energy calculation software, we compare and study the crystal structure, electronic band structure and optical properties of these different isomers in k-space under periodic boundary conditions. Moreover, the corresponding changes in the structure, electronic energy band structure and light performance of different isomers under different static external pressures are also investigated.
More and more novel machine learning methods have speed up the search of molecular conformational isomers. At Alfa Chemistry, we design complex algorithms to generate isomers of different structures and launch automatic search to give accurate prediction of the global optimal structure. Our experts can also describe the geometric shape of the obtained isomers and analyze their stability.
Ab initio methods make it possible to calculate the number of isomers for an alkane of any given carbon content, and the number of isomers of each fragment into which the alkane can be decomposed is able to be count. At Alfa Chemistry, detectable new isomers of carbon-chain (linear) radicals, Cn (n=2-8), are investigated theoretically based on ab initio quantum chemical calculations. Moreover, our high level ab initio calculations can also support the examination of formation mechanisms of C3H and C5H.
Alfa Chemistry provides fast, customized, high-quality services of chemical isomers calculation for global customers. Precisely calculating chemical isomers, providing personalized services with drug research, and assisting in exploring the nature of chemistry are our featured services. Our clients have direct access to our staff and prompt feedback to their inquiries. If you are interested in our services, please contact us for more detailed information.