Rapid Microwave-Assisted Synthesis of .γ-Phosphonic Acid Quaternary Ammonium Antimicrobials for Biomedical Applications
Bibliographic record
Abstract
Novel water soluble γ-phosphonates and phosphonic acid quaternary ammonium compounds (QAC) with different alkyl chain lengths, a dansyl (DNS) fluorescent tag ([RN+Me2(CH2)3P(O)(OR1)2]Br-; R = CH3, C18H37, -DNS-NH- (CH2)3; R1 = Et, iPr, or H) or pyridinium ([C5H5N+(CH2)3P(O)(OR1)]Br-; R1 = iPr, or H) were synthesized in two or three steps (Arbuzov, Menshutkin and bis-dealkylation reactions) under MW conditions within minutes in good yields. These protocols were then compared to thermal heating (TH). Both H2O and MeCN were found to be effective solvents for the Menshutkin and the bis-dealkylation of phosphonate QAC. These reactions were carried out for the first time under MW heating sequentially or in a one-vessel procedure with mineral acids. New compounds were characterized by NMR spectroscopy, HRMS spectrometry and in two instances (17, 20) by X-ray crystallography. We provide X-ray crystallographic evidence for the isolation of the QAC phosphonic acids as the free acids containing the Br- counter ion instead of the previously suggested phosphobetaine internal salts. Self-assembled monolayers of the phosphonic acid QAC prepared in this study are expected to be suitable antimicrobial coatings for metal surfaces used for biomedical applications. Keywords: Arbuzov, didealkylation, environmentally friendly methods, Menshutkin, microwave, monolayers, phosphonate, phosphonic acid, quaternary ammonium antimicrobials, stainless steel coatings.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".