Vibrational spectrum and assignment of 4-cyclopentene-1,3-dione

Effects of π* ← n Excitation in 4-Cyclopentene-1,3-Dione

“…It could alternatively be the b 1 CAO wagging mode 18 . However, the Ј 13 assignment seems preferable since a weak broad hot band at ⌬ ϭ Ϫ300 cm Ϫ1 can be assigned to 10 0 1 13 1 0 , yielding a value of 637 cm Ϫ1 for Љ 13 in agreement with the Raman spectrum (15). Also, since the 14 0 1 band is stronger than 19 0 1 , it would appear that a 2 modes are more efficient than b 1 modes in inducing vibronic activity.…”

“…3, the initial members of the 19 sequences form a prominent progression in approximately 350 cm Ϫ1 . Below 22 000 cm Ϫ1 the progression spacing is 385.0 cm Ϫ1 , corresponding to the a 1 ring-distortion mode Љ 10 in the Raman spectrum (15). Above 22 000 cm Ϫ1 the spacing decreases abruptly to 336.5 cm Ϫ1 .…”

Thielavialides A–E, Nor-Spiro-azaphilones, and a Bis-spiro-azaphilone from Thielavia sp. PA0001, An Endophytic Fungus Isolated from Aeroponically Grown Physalis alkekengi

“…Its IR spectrum showed characteristic absorption bands for hydroxyl (3449 cm –1 ) and 4-cyclopentene-1,3-dione (1702 cm –1 ) moieties. 16 The 1 H and 13 C NMR data (Table 1 ) and the molecular weight difference of 2 Da between 1 – 3 and 4 suggested that 4 is probably an oxidation product of 1 , 2 , or 3 . The major difference in NMR spectra of 1 – 3 and 4 was found to be the absence of the hydroxymethine group at C-3 or C-5 of 4 .…”

“…Its IR spectrum had a strong absorption band at 1713 cm –1 characteristic of an α,β-unsaturated carbonyl moiety of a pentacyclic ring. 16 Analysis of the 1 H, 13 C NMR, and HSQC data (Table 1 ) revealed that 1 contained a tertiary methyl (δ H 1.28 s; δ C 21.2), a secondary methyl [δ H 1.08 d ( J = 6.4 Hz); δ C 21.7], five methylenes of which one is oxygenated [δ H 4.26 ddd ( J = 18.8, 3.6, 2.0 Hz), 4.56 dd ( J = 18.8, 2.0 Hz); δ C 59.0], and two oxymethine groups [δ H 4.74 brd ( J = 2.8 Hz); δ C 76.9 and 3.76 dqd ( J = 12.0, 6.4, 2.0 Hz); δ C 67.1]. It also contained five quaternary carbons consisting of one mono-oxygenated (δ C 81.4), one dioxygenated (δ C 95.4), and two olefinic (δ C 166.4 and 132.4) carbons, and a ketone carbonyl (δ C 204.6).…”

Spectroscopic studies, quantum chemical investigations, and in silico and in vitro scrutiny of the diuretic drug trichlormethiazide adsorbed onAuNPs

“…Molecular structure and spectral investigations of molecules can provide in‐depth knowledge of the relationship between molecular architecture and bioactivity 48,49 . The vibrational spectra of sulfonamides, benzothiadiazines, dichloromethyl, and its derivatives have been subjected to spectroscopic and quantum chemical investigations 50–52 …”