Structural Characteristics of a Partially Planarized Triarylmethyl Cation with Unsymmetrical Push-Pull Structure

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photophysics

Background:

• Triarylmethyl carbocations are versatile molecular building blocks.
• Controlling solid-state packing is crucial for tuning material properties.
• Diphenyl ether and carbonyl groups offer unique electronic characteristics.

Purpose of the Study:

• To synthesize and characterize a novel class of triarylmethyl-based carbocations.
• To investigate the influence of counter anions on crystal packing and photophysical properties.
• To understand the structure-property relationships governing their solid-state behavior.

Main Methods:

• X-ray crystallographic analysis to determine molecular packing.
• Spectroscopic measurements (UV-Vis-NIR) to evaluate photophysical properties.
• Pair Interaction Energy Decomposition Analysis (PIEDA) for computational insights.

Main Results:

• A new class of carbocations with helical plane frameworks was synthesized.
• Crystal structures revealed unique packing patterns dependent on counter anions.
• Panchromatic absorption and near-infrared absorption (λ_onset = 1030 nm) were observed.
• Intermolecular charge transfer transitions were identified as the origin of NIR absorption.

Conclusions:

• The solid-state photophysical properties are significantly modulated by anion-dependent packing.
• Electrostatic interactions between cations and anions dictate the observed supramolecular structures.
• These findings offer a pathway for designing novel materials with tailored optical properties.