Vibrational spectroscopy of the borate mineral henmilite Ca₂Cu[B(OH)₄]₂(OH)₄.
Henmilite is a triclinic mineral with the crystal structure consisting of isolated B(OH)(4) tetrahedra, planar Cu(OH)(4) groups and Ca(OH)(3) polyhedra. The structure can also be viewed as having dimers of Ca polyhedra connected to each other through 2B(OH) tetrahedra to form chains parallel to the C axis. The structure of the mineral has been assessed by the combination of Raman and infrared spectra. Raman bands at 902, 922, 951, and 984 cm(-1) and infrared bands at 912, 955 and 998 cm(-1) are assigned to stretching vibrations of tetragonal boron. The Raman band at 758 cm(-1) is assigned to the symmetric stretching mode of tetrahedral boron. The series of bands in the 400-600 cm(-1) region are due to the out-of-plane bending modes of tetrahedral boron. Two very sharp Raman bands are observed at 3559 and 3609 cm(-1). Two infrared bands are found at 3558 and 3607 cm(-1). These bands are assigned to the OH stretching vibrations of the OH units in henmilite. A series of Raman bands are observed at 3195, 3269, 3328, 3396, 3424 and 3501 cm(-1) are assigned to water stretching modes. Infrared spectroscopy also identified water and OH units in the henmilite structure. It is proposed that water is involved in the structure of henmilite. Hydrogen bond distances based upon the OH stretching vibrations using a Libowitzky equation were calculated. The number and variation of water hydrogen bond distances are important for the stability off the mineral.
Stretching frequency versus bond distance correlation of OD(H)⋯Y (Y N, O, S, Se, Cl, Br, I) hydrogen bonds in solid hydrates
From a compilation of spectroscopic and structural data of solid hydrates 61 different compounds containing more than 250 OD(H)⋯Y groups have been selected, for which uncoupled OD stretching frequencies, hydrogen bond distances and assignments of sufficient reliability and accuracy are available. ν(OD) versus R(O⋯Y) and R(H⋯Y) diagrams and calculated correlation curves are presented for Y  N, O, S, Se, Cl, Br, I. Depending on the scatter of points and the number of data included in the plots the predictive value and the statistical significance varies from very high for O, S and Cl acceptors down to rather poor for Br and I acceptors. At equal bond distances the frequencies may differ by up to about 150 cm−1 depending on the specific chemical nature of the proton acceptors included in a plot, while the influence of different cation—water contacts is less significant and distinct. Anion effects play, therefore, a dominant role in producing large scatters, while action effects and experimental inaccuracies are of minor importance. Furthermore it is shown, that the relation between ν(OD) and ν(OH) frequencies is almost perfect and the frequency—distance correlations involving ν(OD) are also representative without serious restrictions for corresponding correlations involving ν(OH).
Antitumor activities of (2"R)-4'-O-tetrahydropyranyl-adriamycin (THP) and its combination with other antitumor agents on murine tumors.
(2''R)-4'-O-Tetrahydropyranyladriamycin (THP) is a new derivative of doxorubicin (adriamycin, ADM). The concentrations of THP and ADM required to inhibit by 50% the growth of a cultured L1210 cells was 0.003 microgram/ml and 0.016 microgram/ml, respectively. Various therapeutic designs of combinations of THP with other antitumor agents were investigated in vivo using the L1210 murine leukemia. The combination of THP with cytosine arabinoside (Ara-C), cyclocytidine hydrochloride (Cyclo-C), 6-mercaptopurine (6-MP) and cyclophosphamide (EX) showed a great effectiveness following daily intraperitoneal treatment from days 1 to 10. High therapeutic effects were also obtained with the combinations of THP with Ara-C, Cyclo-C, vincristine (VCR) and EX following intravenous combination therapy one day following implantation of L1210 leukemia. Schedule dependency and its therapeutic efficacy of THP were examined. THP showed almost the same antitumor activity on the solid-type sarcoma-180 or solid-type Ehrlich carcinoma as ADM by intraperitoneal or intravenous treatment. THP showed some superior activity to ADM in the advanced stage of L1210 leukemia. High antitumor activity of THP on murine leukemia L1210 has been reported by Tsuruo et al. (Cancer Res. 42: 1462-1467, 1982) and was also confirmed. THP gave many mice cures, especially in the intravenous treatment.