Search for chemicals

Search can be conducted by CAS, name, SMILES, or ChemID. The ChemID is a long string of the following format 323eca7f-fe36-6959-a6fd-1ae6839278b0; therefore, it is highly unlikely that someone uses this function. Other identifiers, however, can be used as shown in the following examples.

Search by name

The name can be specifed as a string and three options of "ExactMatch" (default), "StartWith", and "Contains" are available. It is possible to find multiple chemicals for a specified name; the results are returned as a list of Dict, with each item referring to a single chemical with a unique ChemId.

chem_name = "caffeine"
options = ["ExactMatch", "StartWith", "Contains"]
for option in options:
    res_chem_name = qs.search_name(chem_name, options=option)
    print(f"Found {len(res_chem_name)} chemicals for {option} option")
res_chem_name = qs.search_name(chem_name, options="ExactMatch")
cas_number = [chem["Cas"] for chem in res_chem_name]

As you can see, the exact match for caffeine found fewer results, but more chemicals are found for compund names that starts with or contains the word caffeine.

Search by CAS and SMILES

The cas number must be an integer without the customary dash, e.g. 50000 instead of "50-00-0" that is the CAS number of formaldehyde. The wrapper function, however, accepts both values.

casrn = "50-00-0"  # formaldehyde
res_chem_cas = qs.search_CAS(casrn)
print(f"Found {len(res_chem_cas)} chemicals for CAS number {casrn}")
print(
    f"The chemical is called {res_chem_cas[0]['Names'][0]}, with SMILES {res_chem_cas[0]['Smiles']}, and ChemId {res_chem_cas[0]['ChemId']}"
)

We can also search for the same chemical using SMILES:

smiles = "C=O"  # formaldehyde
res_chem_smiles = qs.search_smiles(smiles)
print(f"Found {len(res_chem_smiles)} chemicals for SMILES {smiles}")

Searching by the CAS RN gives a unique answer (note that a CAS RN refers to a unique chemical, but it does not mean that a chemical is identified by a single CASRN. Multiple CAS RN can refer to the same chemical). Searching by SMILES can find more than a single chemical, as you can see in the above call with C=O that is the SMILES string for formaldehyde.

Next Step

How to extract experimental data for a chemical.