NMRPen© NMR Shift Prediction for Windows 98,2000,XP®

Introduction -- Chemists that use C-13 NMR for organic molecular structure analysis need accurate chemical shift predictions. NMRPen combines a database of more than 73000 assigned chemical shifts with proven NMR shift predictions methods to make NMR shift predictions. To estimate a set of shifts a user draws the chemical structure, then selects the NMR Shifts menu item. Within seconds a set of shifts computed and displayed. NMRPen also includes ChemPen3D for molecular mechanics.

How does NMRPen work? -- NMRPen encodes each atom's local electronic and connective environment into unique number codes. Each assigned chemical shift is matched with a unique code set. NMRPen's database contains more than 73,000 shift/code entries. To make a prediction NMRPen computes the codes for an atom then searches for a match in the database. Absent exact or partial matches NMRPen combines a variety of known NMR Shift prediction algorithms with the database shifts to compute the estimated shifts. References

Is NMRPen fast? -- This will depend on the speed of your computer and the current state of the NMRPen shift library. On an older 75MHz Pentium® estimating the 19 shifts of Androstenedione required less than two seconds. Predictions will be faster for molecules with many exact matches and for highly symmetrical molecules.

How Accurate is NMRPen? -- Because NMRPen combines a database with several empirical methods accuracy is hard to predict analytically. Our empirical testing indicates NMRPen a typical NMR shift prediction will be within 3 ppm of the experimental value on average.

What is encoding? -- Encoding is numerical representation of an atom's environment using a simple set of simple rules. The number of encoding schemes is virtually infinite. NMRPen's model was inspired by molecular connectivity analysis and includes atom types, hybridizations, bonds and charges. NMRPen's encoding scheme is not limited to tabulating chemical shifts.

Can I add my own shifts? -- Yes. To add your own shifts, draw your chemical structure then select NMR Shifts to launch the NMR tool. A set of predicted shifts are generated. Enter your own shifts, if needed in the Add Shift window.

System Requirements -- NMRPen runs on Windows® 95,98,NT,2000, XP. Recommended minimum requirements are a Pentium , 32MB for Windows® 9X, 64MB for Windows NT,2000, XP®, 8MB free HDD. As with all versions of Windows® more memory is better. For email delivered versions: Microsoft Installer Engine installed(It's usually present).

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