Ring-cluster descriptor

However, the current method does have drawbacks. The first is related to the limitations of the ring hashcode descriptor for clustering, as discussed in Section 6.2.4.1. However, this is currently being addressed through the development of a new molecular descriptor. The second is the relatively resource-intensive nature of the method it requires significantly more time to apply than a Top X method. 

Equation 6 (Table XIV) indicates that lipophilicity and molar reffactivity of the substituents at position 6 are important determinants of activity against S. aureus. There is a parabolic relationship seen with these same descriptors for the substituents at position 7. Comparison of equation 6 for S. aureus with equation 7 (Table XV) for Ps. aeruginosa indicates a different QSAR. An ethyl substituent at position 1, minimiun width (Bl) of the substituent at position 6, and the appearance of a piperazinyl ring in position 7 all appear in equation 7. The parabolic relationship of lipophilicity and MR seen in equation 6 for substituents at position 7 is found also in equation 7 indicating that there are optimiun lipophilicity and molar refraction ranges for the 7-substituent. At the same time, it must be noted that many of the values for the parameters listed in Tables IV and V show clustering which can bias the results. 

A scrutiny of the structures of the all-metal [BegZn2] " cluster reveals that the Zn-Zn bond can not only be stabilized by the Bej units alone but also by the Bej and Bc4 rings as well. Moreover, the agenda of stability in all-metal clusters cannot always be settled from the standpoint of aromaticity measures. This rather requires an in-depth analysis of all the allied global and local descriptors that possibly play an inevitable role in the stability of metal clusters. The existence of bond-stretch isomerism in the metal clusters is established. 

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