Researchers detected HNCOH+ in the interstellar medium for the first time in the Galactic Center molecular cloud G+0.693-0.027, Astrobiology Web reported. The detection used ultra-deep broadband spectral surveys with the Yebes 40-m, IRAM 30-m, and APEX telescopes in a survey that covered nearly 150 GHz of bandwidth between 31 and 275 GHz while targeting the same region where H₂NCO⁺ had previously been detected.
The team reported a column density of (9.9 ± 0.5)×10¹² cm⁻² for HNCOH+, a figure that measures the amount of the molecule along a line of sight through space. They also reported an abundance relative to H₂ of (7.3+1.3−1.0)×10⁻¹¹, a ratio comparing the molecule’s abundance to that of molecular hydrogen. Researchers derived both figures from observations of the Galactic Center molecular cloud G+0.693-0.027.
Only five out of roughly 350 detected interstellar molecules contain the isocyanate functional group (NCO), which is essential for peptide bonds in proteins. The group is a critical substructure in peptide bonds, which are fundamental to protein formation. Previous detections in this category include isocyanic acid (HNCO) and its most stable N-protonated isomer H₂NCO⁺.
The HNCOH+/H₂NCO⁺ ratio in the detected molecular cloud is 3.8+0.5−0.4, and researchers based this figure on a measured H₂NCO⁺ column density of (2.6 ± 0.3) ×10¹² cm⁻². This ratio supports recent kinetic calculations favoring the formation of HNCOH+ over H₂NCO⁺. It challenges assumptions about thermodynamic stability dictating isomer abundances in the interstellar medium.
The detection expands the known inventory of interstellar molecules containing the isocyanate functional group, which is critical for prebiotic chemistry. The discovery provides new insights into the chemical processes that may have contributed to the formation of life’s building blocks in space.
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