Synthesis and characterization of sulfonate and phosphonate functionalized monolayer protected gold clusters
Bibliographic record
Abstract
Gold clusters protected with self-assembled monolayers of sodium, 10-mercaptodecanesulfonate, HS(CH2)10SO 3Na, and 11-mercaptoundecanylphosphonic acid, HS(CH2) 11PO3H2, were synthesized to provide negatively charged nanoparticles. The negatively charged end groups of the sulfonate- and phosphonate-monolayers protected clusters, SO3-MPCs and PO 3-MPCs, allowed the particles to be water soluble in addition to be stable in air, and can be dried and redissolved without change. Modifications of experimental conditions, namely the thiol:gold ratio, gold concentration and the type of surfactant, yielded MPCs of 1.8--5.7 nm core diameters with a broad range of size dispersity, and solubilities. Transmission electron microscopy, proton nuclear magnetic resonance (1H NMR), UV-Visible and infrared spectroscopies, thermogravimetric and zeta-potential analyses were consistent with nanoparticle formation. The chain conformation, dynamic behavior and ordering of SO3-MPCs and PO3-MPCs were further investigated by solid-state NMR. Despite the high surface curvature of the nanoparticles and the bulky end groups, medium length chains of SO 3-MPCs (C10) and PO3-MPCs (C11) showed a high degree of organization and restricted mobility when compare to long chains of alkanethiolate MPCs (C18). The more extensive hydrogen bonding interactions between the phosphonic acid groups led to a reduced chain mobility and a higher thermal stability. The PO3-MPCs exhibit a high order-disorder transition, partial decomposition and a very marked hysteresis in the chain recrystallization similar to MPCs stabilized by HS(CH2)nCO2H. Solid-state 31P-NMR allowed studies of the hydrogen-bonded self-assembled structure in the PO3-MPCs as well as in the bulk phosphonic acid. The 1.8 nm-diameter SO3-MPCs produced large aggregates in presence of poly(diallyldimethyl-ammonium chloride) (PDADMAC). However, the encapsulation of individual particles was favored when the same polyelectrolyte
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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) | 0.002 | 0.000 |
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".