ACD/pK_a DB

What's New

Version 4.5 to 5.0

General Interface

• Calculations are faster, by 15 to 200%, depending on calculation options and molecular structure.
• Easier-to-read Results window has white background instead of gray.

• The system can now be trained without opening database, the user can just specify the location of the previously created database through the Results Window:

  

• Internal and user-defined databases can now be examined with the Multiple Record View feature. The displayed data fields, the font, and the zoom level can be chosen after right-clicking to access the pop-up menu.

You can upgrade the indices of database records for more rapid substructure search.

Algorithm

An improved algorithm is now in place. Version 5.0 now uses:

• 932 reaction centers with 1564 Hammett-type equations;
• 618 structures for estimation of pK_a0 for some classes of compounds;
• 762 substituents with 3279 electronic (sigma) constants; and
• 42 structural bridges with 126 equations for estimation of transmission effect.

Version 4.0 to 4.5

• Additional mode of pK_a calculation (pK_a for all dissociation centers when all other atoms are neutral).
• Implementation of User database.
• Implemented training system for new calculation mode.
• New look of internal database with IUPAC names and with additional search possibilities.

pK_a Batch

• Inclusion of pK_a Batch into one interface with LogP Batch and LogD Batch allowing the option of their combined calculation (ACD/PhysChem Batch).
• Additional mode of pK_a calculation (pK_a for all dissociation centers when all other atoms are neutral).
• Implemented training system for new calculation mode.
• Output of calculated data into RDF file with the possibility to view reactions of dissociation in ISIS Base with easy determination of deprotonating centers.
• Output of calculated data into table format.
• Ability to restrict range of calculated pK_a values.
• Ability to prohibit calculation of amides, sulfonic and sulfuric acids (it allows calculation of complex peptides and indicators and increases speed of calculation for such classes of compounds).
• Ability to restrict time for calculation of one structure (program starts calculating next structure after specified time even if the calculation for the current structure is not finished).
• Ability to save or remove backup copy of calculated SDF file.

Version 3.0 to 4.0

• Export to SDF through the History Window.
• Ability to control layout aspects during printing.
• Ability to output text (such as molecule name) from the Results Window.
• Improved predictions for the pK_a values of certain classes of compounds.
• The apparent approximated and apparent exact pK_a values, in addition to microconstants of the current form, are now available.
• Capability to turn off calculation of amides or sulfonic acid groups.

The ChemSketch Window interface and the ACD/ISIS Add-in that are part of the ACD/pK_a DB package have improvements that are described in their respective documents.