Group 13 Complexes of Chelating N₂O₂ⁿ⁻ Ligands as Hybrid Molecular Materials

Abstract

Recent synthetic advances have afforded opportunities for the creation of a wide range of potentially tetradentate N O ligands. When combined with group 13 elements, robust functional molecular materials can be realized. This concept article describes advances surrounding group 13 complexes of selected families of N O ligands, including examples with unique chirality, sensing/detection capabilities, utility in organic electronics, and redox properties. It also highlights the bridge between fundamental main group chemistry and useful application that is being established within this research field.

Interplay of conformational relaxation and hydrogen bond dynamics in the excited states of fluorescent Schiff base anions

“…55 The steady state spectra of salampy À , HBAP 2À and salophen 2À in methanol (MeOH) has been recorded afresh to reproduce our recent reports. [33][34][35] Steady state spectra thus indicate the dependence of the excited state phenomena in the Schiff base anions on multiple parameters of the fluid medium in which it resides.…”

“…32 However, the Al( iii ) complex of this Schiff base has a larger fluorescence quantum yield ( ϕ f ) and a longer fluorescence lifetime ( τ f ), possibly because they are more rigid. 35 Hence, a systematic understanding of the factors that determine the strength of fluorescence complexes has begun to emerge from this series of studies.…”

Tuning the Properties of Azadipyrromethene-Based Near-Infrared Dyes Using Intramolecular BO Chelation and Peripheral Substitutions

“…Near-infrared (NIR) dyes are of great interest for many applications including biological sensing and imaging, photodynamic therapy, NIR photodetection, and solar energy conversion. − In particular, dipyrromethene- and azadipyrromethene-based dyes have attracted a lot of attention because of their tunable and strong absorption in the visible-to-NIR range and fluorescence properties. − These are π-conjugated bidentate ligands that are typically coordinated with difluoroboryl (BF 2 , known as BODIPY and aza-BODIPY) but can also be coordinated with other Group 13 elements and transition metals. ,, Approaches to red-shifting the optical properties include introducing electron-rich/electron-poor functional groups to create a push–pull effect, extending conjugation, and rigidifying the molecule via fused rings. , One underexplored strategy to red-shifting the absorption spectra is to use intramolecular BO bonds. Here, hydroxide groups are added to the ortho position of the proximal phenyls, resulting in a tetradentate N 2 O 2 n –1 ligand that can coordinate with transition metals or Group 13 elements such as boron, thus rigidifying the structure by restricting the proximal phenyls from rotating. , …”

“…Here, hydroxide groups are added to the ortho position of the proximal phenyls, resulting in a tetradentate N 2 O 2 n−1 ligand that can coordinate with transition metals or Group 13 elements such as boron, thus rigidifying the structure by restricting the proximal phenyls from rotating. 13,14 Azadipyrromethenes differ from dipyrromethenes in that the carbon that connects the two pyrrole rings is replaced with nitrogen. This substitution red-shifts the absorption spectra and increases the electron affinity (EA).…”

Enhancing Light‐Absorption and Luminescent Properties of Non‐Emissive 1,3,4,6,9b‐Pentaazaphenalene through Perturbation of Forbidden Electronic Transition by Boron Complexation

“…Herein, we report that the formation of a boron complex structure is valid for enhancing light-absorption and subsequent luminescent properties through the perturbation of the symmetry-forbidden HOMOÀ LUMO transition. So far, various boron complexes have been reported, [20][21][22][23][24][25][26] and it is known that their emission behaviors have usually been attributed to the molecular rigidity induced by the boron atom. Our approach focuses on how the Lewis acidity of the boron atom can be utilized to transform a non-luminescent scaffold to a luminescent molecule.…”