The Effect of Substituents on Characteristics of Functional Material: Consequences of Fusing Schiff Bases and Some of Its Proton Substitutes on Isobenzofuran

Abstract

Research on functional materials is one of the hot technology-related topics. Isobenzofurans and Schiff bases are important building blocks for functional materials. In this study, fundamental aspects of hybrid structures were studied based on B3LYP calculations. The results confirm that fused ortho-amino Schiff bases can have significant impact on the electronic structure of isobenzofuran. The derivatives are unique structures, the magnetic (NICS(0)) / geometric (HOMA) data illustrate that they exhibit the highest π -system localization known for aromatic compounds. The data also provide evidence that the elements in groups 1A, 2A, and 3A can induce a ring current, which is described by “percent aromatic character” with respect to the reference structure. The moderate induction of aromaticity in the fused chelates is associated with significant localization of the atomic charges (APT scheme). However, this computational organic chemistry study identifies for the first time in the chemical literature structures that can be described as aromatic metalla-hetero[14]annulenes (metal-based polycyclic aromatic structures). The band gap calculations of the frontier orbitals revealed that these derivatives are better conductors and chromophores at the molecular level than isobenzofuran. This approach suggests that similar chelates may be used to fine-tune the physical properties of building blocks of functional materials. From a fundamental organic chemistry point of view, the molecular changes are unique and novel as it appears from the chemical literature.

Key Words:

• isobenzofuran
• Schiff base
• DFT
• NICS
• HOMA

ACKNOWLEDGEMENT

We thank Al-Hussein Bin Talal University for the generous support of this research through the research grant 2008/78.

Notes

^a Corrected to the (b)-tautomer.

^b Based on [(NICS-chelate) ÷ (−5.4)] × 100%. The number (−5.4) is the NICS of the C₃N₂ ring in IN-b.

^a Corrected to the (b)-tautomer.

^b Based on [(NICS-chelate) ÷ (−5.4)] × 100%. The number (−5.4) is the NICS of the C₃N₂ ring in IN-b.