count of certain type atoms

Hello,

I would be very appreciate it if you could give me some advice. I need to
calculate a number of structural parameters for the QSAR analysis. Could
you please suggest me the way to count:

1. The number of atoms in largest
pi-chain (it requires the search of the largest fused aromatic ring and
counting the number of atoms on it);

2. The number of atoms in largest acyclic chain
(this means to find the longest acyclic fragment in the structure and count its
atoms).

Unfortunately,
I couldn’t  find  an appropriate way to calculate current terms
using Chemical Terms expressions in Instant Jchem.

Thanks in
advance!

No "canned" Chemical Terms functions exist for this. If you are OK with writing some code, you can write a program using the Marvin API.

Alternatively, you might try to break the molecule into pieces using a Standardizer transform that cleaves all ringatom-chainatom bonds. You will get a list of fragments. Then you can use search queries to filter out acyclic fragments, aromatic ones (those not containing aliphatic atoms), and atomCount() function of Chemical Terms to count their atoms. Multistep work, but seems doable without programming.

Gyuri wrote:

No "canned" Chemical Terms functions exist for this. If you are OK with writing some code, you can write a program using the Marvin API. Alternatively, you might try to break the molecule into pieces using a Standardizer transform that cleaves all ringatom-chainatom bonds. You will get a list of fragments. Then you can use search queries to filter out acyclic fragments, aromatic ones (those not containing aliphatic atoms), and atomCount() function of Chemical Terms to count their atoms. Multistep work, but seems doable without programming.

Thank you Gyuri for the quick reply and useful suggestions! I'll try it.