Previous studies on brazilein have demonstrated color changes caused by pH variations. This study further explores the potential of ethanol extract from sappan wood (Caesalpinia sappan L.) as a metal detection agent.
This study supports the Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation), by advancing environmentally friendly detection techniques and contributing to environmental and public health monitoring.
Through visual observation and UV analysis, color changes in sappan wood extract can be clearly observed. Computational analysis was also performed to evaluate stability and complex formation energy.
Sappan wood extract exhibits a yellow color; when Pb(NO₃)₂ and Pb(OAc)₂ were added, the color changed to pink with maximum absorbance values at λmax = 462 nm and λmax = 512 nm.
The addition of FeCl₃ and Fe(NO₃)₂ resulted in a cream-colored appearance with maximum absorbance at λmax = 436 nm and λmax = 454 nm.
The addition of CuSO₄ produced a peach-colored appearance with maximum absorbance at λmax = 444 nm and λmax = 500 nm.
Chelate formation stability, calculated using Density Functional Theory (DFT), showed that the Fe complex was the most stable, with the highest interaction energy value E(2) of 1907.83 kcal/mol.
The Cu complex demonstrated highly stable formation with an energy value of 824.90 kcal/mol, while the Pb complex showed less stable formation with an energy value of 296.71 kcal/mol.
Author:
Prof. Dr. Nanik Siti Aminah, M.Si.
Rasayan Journal of Chemistry
Vol. 18 | No. 4 | 2556–2563 | October–December | 2025
Article type: Research article.
This article is reposted from the Popular Scientific Article page of Universitas Airlangga (UNAIR) and has been adapted for publication on the Chemistry UNAIR website.
