Theoretical Study of the Structure−Property Relationship in Phosphole Monomers

Abstract

Use of the DFT method with the B3LYP functional offers an efficient way for determining geometries of phosphole structures. It also provides inversion barriers in good agreement with experiment. The molecular orbital MP2 method is better suited to calculate the relative stability of the considered isomers. Combination of geometric (Julg index) and magnetic (NICS) criteria leads to an interesting approach to analyze the pi-electron delocalization and/or aromaticity in conjugated heterocyclic systems and can be used for investigation of much larger oligomers. It thus allows us to confirm that planarizing the phosphorus atom in phosphole monomers leads to a greater conjugation over the butadienic pi-system and that substituents, characterized by a strongly pronounced pi-system, exhibit a large extent of conjugation with the pi-diene moiety of the heterocyclic system. In push-pull systems such as 2-BH2-5-NH2-1H-phosphole, the electron delocalization along the pi-diene system is even more pronounced than in phospholes with strongly pronounced pi-systems. The employed approach is also used to analyze the relationship between electron conjugation and the phosphorus inversion barrier. More relevant for chemical applications is the result that the computational study provides a method of fine-tuning of phosphole building blocks, which may enable us to obtain higher pi-conjugation along the polymer backbone.

Analogy between sulfuryl and phosphino groups: the aromaticity of thiophene-oxide

“…Elements of the third row of the periodic table, however, can have different oxidation state forming hypervalent species. Recently, we have shown [7] that such change at the heteroatom switches the slight aromaticity of phosphole [8][9][10][11][12][13][14][15][16][17] to the slight antiaromaticity of phospholeoxide, resulting even in chemical consequences.…”

Using three major criteria to evaluate aromaticity of five-member C-containing rings and their Si-, N-, and P-substituted aromatic heterocyclics

“…During the last few years, great interests have been taken in five-member heteroaromatic (e.g., aza-, phospha-, and etc) rings and their "aromatic character" [1][2][3][4][5][6][7]. So it is very significant to study the aromaticity and other physicochemical properties of these compounds.…”

Studi Semiempiris Struktur Molekul Dan Band Gap Monomer Dan Dimer 1,3,4 Tiadiazol Dan Derivatnya

“…Beberapa polimer derivat tiofen bersifat konduktor yang transparan. Menurut Deliere, adanya substituen aseptor elektron π pada monomer dan polimer dapat memperbaiki efisiensi delokalisasi elektron sepanjang sistem π diena dan mengakibatkan perubahan sifat hantaran listrik dan optik nonlinier material [4] . Brocks and Tol, Nebutoki and Koezuka mengemukakan bahwa polimer/oligomer senyawa organik heterosiklik (mengandung S, N dan O) yang mempunyai π berkonyugasi, berpotensi sebagai material semikonduktor [5,6] .…”

“…Polyisothianaptene (PTIN) mempunyai Eg 1 eV, tetapi polimer ini kurang stabil karena sangat mudah teroksidasi, sehingga penggunaannya semakin sempit. Menurut Delaere substitusi gugus donor (-NH2, -N(CH3)2) dan aseptor (-BH2) elektron π pada posisi α pada monomer fosfol (C4PH4) dapat memperbaiki efisiensi delokalisasi elektron sepanjang sistem π diena dan dapat merubah sifat hantaran listrik dan optik nonlinier material [4] .…”