Chem Structure: Compare Psychotropic Molecules

What it shows

Chem Structure puts two psychotropic molecules next to each other so you can see how chemistry shapes their behavior. Each panel shows a 2D structure (rotatable) or an interactive 3D model, plus molecular formula, molecular weight, cLogP and a lipophilicity label, topological polar surface area, estimated aqueous solubility, ionization at pH 7.4, the signal entry point, and the year the drug was introduced or synthesized. Curated notes describe the fat- versus water-attracting parts of the molecule, its protein-binding region, receptor-binding region, membrane transport, and signal cascade. Active metabolites are linked so you can load them into the other panel. The library holds 139 structures.

Druglikeness and CNS access

Each molecule is placed on colored range bars for molecular weight, cLogP, polar surface area, hydrogen-bond donors and acceptors, and rotatable bonds. Chips summarize three checks the tool computes:

Check	Rule used by the tool
Lipinski	Flags two or more of: MW over 500, cLogP over 5, more than 5 donors, more than 10 acceptors
Veber	Oral-favorable when rotatable bonds are 10 or fewer and polar surface area is 140 Ų or less
CNS profile	CNS-penetrant when polar surface area is 90 Ų or less and MW is 450 or less; limited entry up to 140 Ų

Comparing two drugs

The comparison summary reports structural similarity (Morgan/ECFP4 Tanimoto), shared FDA indications (Jaccard overlap), and whether the two drugs share a pharmacologic class. When a pair are enantiomers, the tool explains that 2D fingerprints cannot see chirality. Built-in lineages, such as amitriptyline to fluoxetine, describe what changed chemically in the newer agent and why the change was expected to help. A single-medication mode and a sortable filter-and-rank table of the whole library are also available, along with links to the Medicinal Chemistry at the Bedside and Pregnancy and Breastfeeding chapters.

Limitations

This is an educational reference. Properties are computed with RDKit from each drug's SMILES, solubility uses the ESOL model and gives the neutral-form value (marketed salts are far more soluble), the 3D view is a single computed conformer, and pKa values are approximate literature figures. Region and lineage notes are curated teaching summaries, not a substitute for primary medicinal-chemistry sources.