138 JOURNAL OF COSMETIC SCIENCE recorded with a Perkin-Elmer FT-IR 1760 X. UV spectra were recorded on a HP 8452A diode array spectrometer. Irradiance measurements were performed with UV meter 70380 from Oriel Instruments (response between 280 nm and 400 nm, with a maxi­ mum sensibility at 3 70 nm). Irradiation was carried out (a) using a 150-W xenon lamp (the xenon lamp emits a continuous spectrum of light, ranging from ultraviolet through visible to infrared (Figure 2), and the lamp output was sent through a water filter (5-cm pathlength) to remove most of the radiations), or (b) under natural sunlight from 12:00 h to 15 :30 h (solar time) in May and June 2002 in Toulouse (at latitude 43° North), France. Molecules were modelled by the software Pimms Molecular Modelling SystemVI.47.a. The predicted log (P) values, partitioning ratio between water and octanol, were calculated using Tsar software (Silicon Graphics, Iris Indigo X524/4000). PREPARATION OF ClO-DBM According to the procedure described by Clark and Miller (18,19) and Marzinzik and Felder (20), an aqueous solution of tetra-n-butylammonium fluoride (0.017 mol) was added to BM-DBM (0.010 mol). By heating this mixture to 80°C, under reduced pressure (evaporator) for three hours, water escaped, leaving an anhydrous yellow residue. This residue was dissolved in THF (25 ml), and 1-bromodecane (0.030 mol) was added. Then, the mixture was stirred at 70°C for two hours. The solution was evaporated, giving a yellow viscous residue. This was purified on a silica column, with dichloro­ methane as eluent (42% yield). 1 H NMR (400 MHz, CDC1 3 ), oppm' J H2 : 8.00 (m, 2H, J = 8.8 H 6 ) 7 .93 (m, 2H, J = 8.4 H 8 ) 7.46 (m, 2H, J = 8.4 H 9 ) 6.94 (m, 2H, J = 8.8 H 1 0) 5.11 (t, lH,J = 6.6 H 11 ) 3.87 (s, 3H, Hu) 2.12 (m, 2H, H 18 ) 1.34 (s, 9H, H 14 ) 1.28 (m, 16H, H 16 and Hp) 0.89 (t, 3H, J = 6.7 H 15 ). 1 3C NMR assignments were ascertained with the help of 1 H-1H COSY, 1 H-13C HSQC and HMBC spectra. 1 3C NMR (100 MHz, CDC1 3 ), oppm: 196.1 (C 2 ) 195.1 (C 1 ) 163.9 (C 3 ) 157.3 (C4) 133.9 "'e -iE E 10 2 10· 1 500 1000 1500 WAVELENGTH (nm) 2000 2400 Figure 2. Spectral irradiance of 150-W xenon lamp, showing percentage of total irradiance in specific UV, visible, and near infrared spectral ranges.

NEW LONG-CHAIN UV ABSORBER 139 (C5 ) 131.2 (C 6 ) 129.5 (C7) 128.8 (C 8 ) 125.9 (C 9 ) 114.2 (C 10 ) 57.7 (C 11 ) 55.7 (C 12) 35.3 (C 13) 32.1-28.6 (Cn) 31.2 (C 14) 29.9 (C 18) 22.9 (C 16) 14.3 (C 15 ). IR (KBr), vcm-l: 2924 1692 1663 1602-1464 1262 1171 844. MS (ES, MeOH, positive mode) m/z = 451 [M + H+]. Anal. Calcd for C30H420 3 : C, 79.96 H, 9.39 0, 10.65%. Found: C, 80.07 H, 9.69 0, 10.87%. PREPARATION OF THE CREAM We used a water-in-oil preparation obtained from Dipta (Aix-en-Provence, France) in which we incorporated 1 % in weight of each molecule: BM-DBM and/or ClO-DBM. The preparation contained dicaprylyl carbonate (10%), beeswax (4%), PEG-30 dipoly­ hydroxystearate (3%), polyglyceryl-3 diisostearate (1.5%), disodium EDTA (0.2%), sodium chloride (1 %), methylparaben (0.2%), xanthan gum (1 %), butylparaben (0.3%), glycasil L (0.2%), and water (78.6%). PHOTOST ABILITY ASSAYS The method used was inspired by that of Rudolph (21) and Allen et al. (10). Assays for photostability were performed on small, smooth, quartz plates of 16 cm2. The prepa­ rations were spread on the plates as thin films (1 mg cm-2). The average film thickness was calculated from the sample weight, the sample area, and the specific gravity of the sunscreen preparation. The plates were exposed either to the xenon lamp or natural sunlight irradiation. Irradiance measurements were done with the UV meter at the distance the quartz plates had been irradiated. Irradiation of the samples was done at room temperature. The reference background used for UV spectra measurement was the water-in-oil preparation with no sunscreen. This preparation was irradiated under the same conditions as the samples. Tables I and II show the irradiation characteristics. RESULTS SOL VA TOCHROMISM STUDY ClO-DBM was obtained according to the procedure described by Clark and Miller (18,19). The ClO-DBM isolated at the end of the purification was in its beta-diketone form (Figure 1). No trace of the enol form was detected by NMR, IR, or HPLC analyses. Table I Irradiation Conditions under 150-W Xenon Lamp for Preparations Containing 1 % w/w Absorbers Total concentration UV intensity* Irradiation Absorbers (mmol 1- 1 ) (mW cm- 2 ) experiments r BM-DBM 29 10.6 P2 P3 ClO-DBM 21 10.5 Cl BM-DBM/Cl0-DBM (7:3) 19 10.8 Ml Preparation specific gravity = 0.934 g cm- 3 and irradiated area = 16 cm2. * Radiometer: Oriel Instruments. Film Sample weight thickness (mg cm- 2 ) (µm) 1 11 0.75 8 1 11 1 11 0.9 10