Related Experiment Video
Updated: Jun 24, 2025

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
Regioisomerism in Thienothiophene-Based Covalent Organic Frameworks─A Tool for Band-Gap Engineering
Roman Guntermann1, Laura Frey1, Alexander Biewald1
1Department of Chemistry and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität (LMU), Butenandtstraße 11 (E), Munich 81377, Germany.
Abstract:
The craft of tuning optical properties is well-established for crystalline inorganic and hybrid solids. However, a far greater challenge is to tune the optical properties of organic materials systematically by design. We now introduce a synthesis concept that enables us to alter the optical properties of crystalline covalent organic frameworks (COFs) systematically using isomeric structures of thienothiophene-based building blocks (T23/32T) combined with a variety of tetratopic aromatic amines, e.g., the Wurster moiety (W-NH2). This concept is demonstrated for the synthesis of COFs in bulk and film forms and provides highly crystalline and porous isomeric COFs featuring predesigned photophysical properties. The band gap of the framework can be tuned continuously and precisely by chemically doping the pristine W23TT COF with its related constitutional isomer building block. Density-functional theory investigations of COF model compounds indicate that the extent of π-conjugation is among the key characteristics enabling the band-gap engineering.
More Related Videos
08:42Microfluidic-based Synthesis of Covalent Organic Frameworks COFs: A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface
Published on: July 10, 2017
08:43Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors
Published on: November 7, 2016
Related Concept Videos
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Band Theory
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
Stereoisomerism of Cyclic Compounds
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
UV–Vis Spectroscopy: Woodward–Fieser Rules