• Top library match: [5-(6-aminopurin-9-yl)-4-hydroxy-2-[[[[3-hydroxy-2,2-dimethyl-4-oxo-4-[[3-oxo-3-(2-tetratriaconta-16,19,22,25,28-pentaenoylsulfanylethylamino)propyl]amino]butoxy]-oxidophosphoryl]oxy-oxidophosphoryl]oxymethyl]oxolan-3-yl] phosphate #17980

• The library candidate contains amide, ester, phosphate, and hydroxyl groups, yet the spectrum shows no amide I (~1650 cm⁻¹), amide II (~1550 cm⁻¹), phosphate (~1200–1000 cm⁻¹), or broad O–H/N–H stretching absorptions.
• Such missing features are inconsistent with an intact, pure compound, suggesting that the sample may consist mainly of the fatty acyl portion, that the polar groups are present at low concentration, or that the measurement window excluded their signatures.
• The 1460 cm⁻¹ band could also contain a contribution from aromatic C=C stretching, as noted by one literature assignment [3]; however, no aromatic C–H stretches (>3000 cm⁻¹) are observed, making a purely aromatic origin unlikely.
• The exact identity of the material remains uncertain without full mid-IR coverage (especially the fingerprint region) and without independent verification of the nucleotide and polar functionalities.

Recommended next steps: Acquire data over the extended range 4000–400 cm⁻¹ to detect potential phosphate, amide, and fingerprint bands. Compare the spectrum with a certified reference sample of the candidate nucleotide-lipid conjugate. Perform confirmatory analysis using mass spectrometry and/or ¹H/¹³C NMR to verify the structure and composition of the sample.