Dimethoxytrityl, often abbreviated DMT, is a protecting group widely used for protection of the 5'-hydroxy group in nucleosides, particularly in oligonucleotide synthesis.
It is usually bound to a molecule, but can exist as a stable cation in solution, where it appears bright orange.
References
Krotz, Achim; Cole, Douglas; Ravikumar, Vasulinga (1999). "Dimethoxytrityl Removal in Organic Medium: Efficient Oligonucleotide Synthesis Without Chlorinated Solvents". Nucleosides and Nucleotides. 18 (6–7): 1207–1209. doi:10.1080/07328319908044664. https://www.tandfonline.com/doi/abs/10.1080/07328319908044664 ↩
"Dimethoxytrityl/DMT (Orange you glad you protected that alcohol?)". Molecule of the Day. 2006-09-05. Retrieved 2022-05-03. https://scienceblogs.com/moleculeoftheday/2006/09/05/dimethoxytrityldmt-orange-you ↩