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Abstract β‐lactams are a chemically diverse group of molecules with a wide range of biological activities. Having recently observed curious trends in²J_HHcoupling values in studies on this structural class, we sought to obtain a more comprehensive understanding of these diagnostic NMR parameters, specifically interrogating¹J_CH,²J_CH, and²J_HH, to differentiate 3‐ and 4‐monosubstituted β‐lactams. Further investigation using computational chemistry methods was employed to explore the geometric and electronic origins for the observed and calculated differences between the two substitution patterns. 

NMR pulse sequences visualizing 1 J CC and n J CC bond connectivity via an intermediate state of 13 C– 13 C double-quantum coherence and 1 H detection are an indispensable tool to solve small-molecule structures at the natural abundance level of 13 C. A longstanding issue with these experiments set up to display 2D spectra with single-quantum frequencies is that in addition to the 1 H– 13 C– 13 C correlations of interest, appearance of HSQC-type artifacts can complicate analysis and obscure J CC connectivities. The origin of these artifacts is described and remedies for their suppression are introduced. They include refocusing of 1 J CH couplings prior to creation of 13 C– 13 C double-quantum coherence, which is known to enhance sensitivity by reducing loss into zero-quantum coherence for pairs of two protonated 13 C. 

Abstract A great diversity of crustacean zooplankton found in inland and coastal waters produce embryos that settle into bottom sediments to form an egg bank. Embryos from these banks can remain dormant for centuries, creating a reservoir of genetic diversity. A large body of literature describes the ecological and evolutionary importance of zooplankton egg banks. However, literature on the physiological traits behind dormancy in crustacean zooplankton are limited. Most data on the physiology of dormancy comes from research on one species of anostracan, the brine shrimp,Artemia franciscana. Anoxia-induced dormancy in this species is facilitated by a profound and reversible acidification of the intracellular space. This acidification is accompanied by a reversible depletion of adenosine triphosphate (ATP). The present study demonstrates that acidification of the intracellular space also occurs in concert with a depletion of nucleoside triphosphates (NTPs) in the Antarctic copepod,Boeckella poppei. LikeA. franciscana, the depletion of NTPs and acidification are rapidly reversed during aerobic recovery inB. poppei. These data provide the first comparative evidence that extreme dormancy under anoxia in crustacean zooplankton is associated with intracellular acidification and an ability to recover from the depletion of ATP. 

Abstract The recently reported¹⁹F‐detected dual‐optimized inverted¹J_CC1,n‐ADEQUATE experiment and the previously reported¹H‐detected version have been modified to incorporateJ‐modulation, making it feasible to acquire all 1,1‐ and 1,n‐ADEQUATE correlations as well as¹J_CCandⁿJ_CChomonuclear scalar couplings in a single experiment. The experiments are demonstrated usingN,N‐dimethylamino‐2,5,6‐trifluoro‐3,4‐phthalonitrile andN,N‐dimethylamino‐3,4‐phthalonitrile.