# Wavelength-dependent reactivity of germanium-based photoinitiators

## TL;DR

This paper studies how different light wavelengths affect the reactivity of germanium-based photoinitiators used in light-driven chemical processes.

## Contribution

The study introduces new insights into how specific wavelengths influence the efficiency and behavior of three germanium-based photoinitiators.

## Key findings

- Quantum efficiencies and absorbance of photoinitiators vary significantly with LED wavelengths between 365 and 495 nm.
- Photobleaching behavior and penetration depth are closely linked to the emission profile of the light source.
- Findings can help optimize photoinitiator performance in biomedical printing and polymerization.

## Abstract

This study investigates the wavelength-dependent reactivity of the three germanium-based type I photoinitiators bis(4-methoxybenzoyl)diethylgermane (Ivocerin®), tris(2,4,6-trimethylbenzoyl)ethylgermane, and tetrakis(2-methylbenzoyl)germane. By systematically varying LED wavelengths from 365 to 495 nm, we quantify quantum efficiencies/absorbance and correlate them with the photobleaching behavior and penetration depths. The results highlight the crucial relationship between the emission profile of the light source and the efficiency of the photoinitiators. These insights are particularly relevant for optimizing light-driven processes in applications such as biomedical printing, adhesives, and spatially controlled polymerization.

The online version contains supplementary material available at 10.1007/s00706-025-03379-5.