Abstract
In the current study, a comparative molecular field analysis (CoMFA) model with the combined activity of polybrominated biphenyls (PBBs) bioconcentration, long-range transport, and the highest infrared signal intensity (weight ratio of 5:4:1) was constructed based on the threshold method and was further evaluated and analyzed. PBB-153 derivatives with improved combined activity values of bioconcentration, long-range transport, and the highest infrared signals intensity were designed based on contour maps of the CoMFA model. The environmental stability and functionality of the derivatives were also evaluated. The constructed model showed good prediction ability, fitting ability, stability, and external prediction ability. The contribution rates of electrostatic and steric fields to the combined activity of PBBs were 53.4% and 46.6%, respectively. Four PBB-153 derivatives with significantly improved bioconcentration, long-range transport and the highest infrared signal intensity (the combined activity value of these three parameters decreased) were screened with good environmental stability and functionality. Results validated the accuracy and reliability, and ability of the generated model to realize the simultaneous modification of the three activities of the target molecule. The binding ability of the designed derivatives to food chain biodegradation enzymes increased, thereby verifying the improvement in the bioconcentration. The half-lives of the derivatives in air and their ability to be absorbed by the plants significantly improved compared to the target molecule, further showing that the long-range transport of derivatives was reduced. In addition, the introduction of the –NO group caused the N =O stretching vibration of the derivatives to increase the infrared signal intensity. The present model provides a theoretical design method for the molecular modification of environmentally friendly PBBs.
Highlights
Polybrominated biphenyls (PBBs) are a class of brominated flame retardants with 209 homologs
The above studies showed that PBBs have definite bioconcentration and long-range transport and are extremely harmful to both the environment and human health
The bioconcentration and long-range transport of 45 PBBs were predicted by the Toxicity Estimation Software Tool (TEST 4.2.1, released by EPA, https://www.epa.gov/ chemical-research/toxicity-estimation-software-tool-test)
Summary
Polybrominated biphenyls (PBBs) are a class of brominated flame retardants with 209 homologs. As an additive flame retardant, PBBs are slowly released into the environment and taken up by the organisms [2]. Even after 40 years of the Michigan pollution incident, PBBs are still detected in the human serum in the Michigan area [8]. Experiments on mice showed PBBs to be carcinogenic [1]; their presence in the human blood [14] and fat [15] can cause potential risks to human health. The above studies showed that PBBs have definite bioconcentration and long-range transport and are extremely harmful to both the environment and human health. Studies based on the related properties of PBBs can provide better insights into their effective mechanism and can help design better and environmentally friendly flame retardants
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