Unambiguous Determination of the 13C and 1H NMR Stereosequence Assignments of Polylactide Using High-Resolution Solution NMR Spectroscopy (Record no. 46963)
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| fixed length control field | 02913nam a2200241Ia 4500 |
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| control field | MX-MdCICY |
| 005 - DATE AND TIME OF LATEST TRANSACTION | |
| control field | 20250625153908.0 |
| 040 ## - CATALOGING SOURCE | |
| Transcribing agency | CICY |
| 090 ## - LOCALLY ASSIGNED LC-TYPE CALL NUMBER (OCLC); LOCAL CALL NUMBER (RLIN) | |
| Classification number (OCLC) (R) ; Classification number, CALL (RLIN) (NR) | B-12757 |
| 008 - FIXED-LENGTH DATA ELEMENTS--GENERAL INFORMATION | |
| fixed length control field | 250602s9999 xx |||||s2 |||| ||und|d |
| 245 10 - TITLE STATEMENT | |
| Title | Unambiguous Determination of the 13C and 1H NMR Stereosequence Assignments of Polylactide Using High-Resolution Solution NMR Spectroscopy |
| 490 0# - SERIES STATEMENT | |
| Volume/sequential designation | Macromolecules, 35, p.7700-7707, 2002 |
| 520 3# - SUMMARY, ETC. | |
| Summary, etc. | Polylactide (PLA)is a biodegradable polyester formed by the ring-opening polymerization of lactide, the cyclic dimer of lactic acid. Many of the physical properties of PLA are influenced by the amount and distribution of the R and S stereocenters in the polymer chain. NMR spectroscopy is the most common technique used to determine the stereosequence distribution of the polymer. The correct determination of the stereosequence distribution is contingent upon the assignment of the peaks in the NMR spectrum to specific stereosequences. Recently, alternative assignments to the commonly accepted stereosequence assignments have been proposed. If any of these alternative assignments are found to be correct, it would invalidate the conclusions of much of the previous work in understanding the kinetics of lactide polymerization and determining the stereoselectivity of new catalysts. The most significant problem is reconciling the commonly accepted peak assignments, which were based upon statistical probabilities, with contradictory connectivity data observed in a HETCOR NMR experiment. To describe the directionality in PLA, we have modified the nomenclature used to describe directionality in peptides and proteins. For PLA, the end containing the carboxylic group is referred to as the C terminus, and the end with the hydroxyl group is the O terminus. We had previously proposed that the central pairwise relationship (isotactic or syndiotactic, denoted i or s)in the 1H NMR spectrum is determined by the stereocenter in the lactic acid unit attached to the O terminus and that in the 13C NMR spectrum it is determined by the central pairwise relationship of the stereocenter in the lactic acid unit attached to the C terminus. One- and two-dimensional NMR techniques, in combination with selective isotopic labeling, were used to show that this relationship is correct and that the commonly accepted assignments are correct. In addition, all of the nondegenerate resonances in the 1H and 13C NMR spectrum of polylactide at the tetrad stereosequence level have been assigned. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Zell, M,T, |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Padden, B.E. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Paterick, A.J. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Thakur, K.A.M. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Kean, R.T. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Hillmyer, M.A. |
| 700 12 - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Munson, E.J. |
| 856 40 - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | <a href="https://drive.google.com/file/d/1gE0n5H7RSx99sG3jTp3dSlCcxImFUKeH/view?usp=drivesdk">https://drive.google.com/file/d/1gE0n5H7RSx99sG3jTp3dSlCcxImFUKeH/view?usp=drivesdk</a> |
| Public note | Para ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | Clasificación local |
| Koha item type | Documentos solicitados |
| Lost status | Source of classification or shelving scheme | Damaged status | Not for loan | Collection | Home library | Current library | Shelving location | Date acquired | Total checkouts | Full call number | Date last seen | Price effective from | Koha item type |
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| Clasificación local | Ref1 | CICY | CICY | Documento préstamo interbibliotecario | 25.06.2025 | B-12757 | 25.06.2025 | 25.06.2025 | Documentos solicitados |