Novel O-propyl, S-propyl, and N-propyl substituted 1,4-naphthoquinones and 1,4-anthraquinones as potential fingermark development reagents for porous surfaces

Lawsone is a 2-substituted-1,4-naphthoquinone derivative, which has been proposed as an alternative to the reagents currently used for fingermark detection on porous surfaces. 2-substituted-anthraquinones, which contain an additional conjugated benzene ring, have a similar chemical structure to that of lawsone. In this study, a new series of 2-substituted-1,4-naphthoquinones and 2-substituted-1,4-anthraquinones were synthesized and completely characterized by(1)H NMR,C-13 NMR, IR, and HPLC-TOF/MS analyses. All newly synthesized 2-substituted-1,4-quinones were investigated for their ability to develop latent fingermarks on porous surfaces, and this ability was compared with that of lawsone. Each fingermark developed was graded using an established method; thus, quantitative data were attributed to each fingermark. It has been demonstrated that the 1,4-quinones react with amino acids present in latent fingermarks on selected paper surfaces to produce faint yellow-orange impressions, which exhibit strong photoluminescence when illuminated with a forensic light source at 440 nm and observed through a red filter. None of the compounds caused background darkening. The results obtained were generally similar to those of lawsone, however, 8-dibromo-2-(propylamino)naphthalene-1,4-dione and 5,8-dibromo-2-(propylthio)naphthalene-1,4-dione yielded better results for copier paper and colored (blue) copier paper used in this analysis. To the best of our knowledge, this is the first study to examine the role of 1,4-anthraquinone derivatives as potential fingermark development reagents. The results indicate that 1,4-quinones have a potential to be used as reagents for enhancement of latent fingermarks.